But the British government turned down the request, fearing the impact that the arrival of Taliban representatives might have on the delicate negotiations between police and the hijackers.
Another hostage was released yesterday - following the three men, three women and two children freed on Monday - from what has become the longest hijack in Britain. The Boeing 727 was captured during an internal Afghan flight on Sunday.
The government in Kabul, which is in the grip of the hardline Islamic Taliban movement, had asked the foreign office if it could fly one of its representatives, thought to be a minister, into Gatwick.
Britain does not have diplomatic ties with the Taliban government, which on Monday described the hijackers as terrorists and urged the British government to storm the plane.
The mood among the hijackers is reported to be calm but the arrival of the Taliban would have introduced an unpredictable and potentially destabilising element. It is thought the minister seeking entry was the Taliban's deputy foreign minister, Abdul Rahman Zahid, who is visiting Germany.
Police hopeful
A spokesman for the Taliban government, Sayed Rahmatullah, speaking before the Taliban request was turned down, said: "If we go to London it will only be to receive our nationals there who are being released. We will not negotiate with the hijackers."
Police at Stansted said they were hopeful of securing the release of the 156 people still on board the Boeing 727. "The fact that we have had nine people released from the aircraft is positive and should be treated in this way. The fact that we are talking and continue to talk is very positive."
John Broughton, the assistant chief constable of Essex police, said last night about 100 police officers, five fire crews and troops including an SAS team remained at the airport monitoring the hijackers, who are reported to be armed with automatic weapons and grenades. Armed police are stationed 50 yards from the plane.
The crisis has already cost the British taxpayer upwards of £1m.
Despite a demand for the release of a rebel leader, Ismail Khan, government sources said the motives of the hijackers remained unclear. A Whitehall source said: "We still do not know why they are here, why they chose to come here or why they left."
Reports from embassies in India, Pakistan and elsewhere suggest part of the motive may be to seek eventual asylum in Britain. While this was not being totally discounted by British authorities yesterday, it was regarded as an odd ploy since the hijackers would automatically face charges for taking the plane, which could lead to a long prison sentence.
The man released yesterday was an Afghan, aged between 40 and 45, who had complained of asthma. Police sharpshooters trained their weapons on him and the exit to the plane as he was pushed from the aircraft and ordered to put down his bags and walk with his hands up towards police.
He was later given oxygen, food and water and was said by Mr Broughton to be "feeling fine".
Since the jet was seized en route from Kabul to the northern Afghan town of Mazar-i-Sharif, shortly after takeoff at 5.30am GMT on Sunday, about 30 hostages have been released in all, including some at stops in Uzbekistan, Kazakhstan and Moscow.
Although Essex police said the hijackers had issued no political ultimatum, they did acknowledge that "there are issues that will be discussed".
A police spokeswoman said: "There is a difference between discussing issues and making demands." Trained negotiators have kept lines open almost constantly with the hijackers since the plane, belonging to the Ariana airline, arrived at Stansted at 2.01am on Monday, although there was an agreed break for about an hour early on Monday morning.
The negotiators operate in teams of three - usually two in a speaking roll with the third coordinating from Stansted police station.
"Negotiations are taking place in a well ordered and logical way," said Mr Broughton. "It's not been pushed on either side. People need to reflect on what is going on." In talks with the hijackers and with freed hostages police were "building up a detailed picture" of the situation on the plane.
Operation Invicta
One of those involved in what is being called "Operation Invicta" is Detective Chief Inspector Win Bernard, who engineered the successful release of 186 passengers and 13 crew after 18 hours on a hijacked Sudanese plane at Stansted in 1996.
Through a grim third day on board, the hostages stayed "remarkably calm", Mr Broughton said yesterday.
A breakfast of omelette and mushrooms at about 7.30am, another generator for air conditioning and the provision of medical supplies to ease upset stomachs, along with hygiene materials for the toilets, lessened but hardly released the discomfort of the remaining passengers.
The plane was full to capacity on take-off and comfort on the Afghan state airline is limited at the best of times. Since a ban enforced by the United Nations on the airline running international flights, Ariana has found it difficult to get parts and its planes are in poor condition.
But the hostages released on Monday, including two girls aged three months and six months, were reported to have been treated well. The infants were given medication for dehydration.
Four members of one family that were released were put up at the Stansted Hilton hotel under police watch. One of the men, bearded and about 5ft 5in, looked fit and smiled as he gathered his belongings. Although he said he spoke no English, police were anxious to keep him from reporters.
A five-strong team of Persian-speaking interpreters brought in from London to assist the family were also prevented from speaking publicly amid fears that even the most innocuous divulging of information about conditions on board the hijacked plane could jeopardise careful negotiations.
One police source said the hijackers were believed to be monitoring media reports through an on-board television. Mr Broughton, said: "There may well be information that becomes available to the negotiators that if it is released may well jeopardise the safety of passengers. I am sure nobody would expect us to jeopardise that."
John Williams, the head of public affairs at Stansted, said just 12 of the 450 flights to and from the airport yesterday had to be cancelled, because the planes were too large to use the reduced runway space available.
The Afghan opposition leader and former president Burhanuddin Rabbani yesterday denied that the hijackers had requested the release of Ismail Khan. "The legal government of Afghanistan categorically denies its involvement in the plane hijacking," Mr Rabbani said in Dushanbe, Tajikistan. "Rumours that terrorists demand the release of the former governor of the Herat province, Ismail Khan, are groundless, and its the Taliban itself that is spreading those rumours."
