The captured crew members of a UK-flagged oil tanker seized by Iran are seen in this first photo from inside the ship.
The image shows an Iranian official speaking to the sailors, who are sat huddled on the floor with their shoes piled up nearby.
Another snap shows an armed member of Iran's forces on the ship.
Reports from Tehran state those on board the Stena Impero are safe and well.
Stena Bulk, the tanker's owner, has said the 23 crew are of Indian, Russian, Latvian and Filipino nationality.
Iran's Revolutionary Guard seized the Stena Impero last Friday, initially claiming it was in violation of international maritime law in the Strait of Hormuz.
Britain said the ship was in Oman’s territorial waters when its was seized, and it was following international law.
It was a tit-for-tat seizure after Britain seized an Iranian tanker off Gibraltar earlier this month.
Theresa May will chair a meeting of the Government's emergency committee Cobra on Monday to discuss the situation as the crisis between Iran and the West deepened.
The Prime Minister is expected to receive updates from ministers and officials on the seized tanker and will discuss the maintenance of the security of shipping in the region.
Mrs May was not present at ministerial Cobra meetings over the weekend - which she spent in her Maidenhead constituency - but was kept informed of developments.
Foreign Secretary Jeremy Hunt will update the Commons on the situation on Monday afternoon, amid reports that ministers are considering freezing Iranian regime assets.
He is expected to tell MPs what further measures the Government will take.
UK ships have been warned to avoid the Strait of Hormuz, a key oil shipping route.
The Swedish-owned, UK-flagged ship and its crew members are being held at the Port of Bandar Abbas.
Marine tracking websites showed the Stena Impero travelling through the Strait of Hormuz towards the Persian Gulf before making a turn north.
It entered Iranian territorial waters and its tracker was turned off.
It was captured just weeks after British Royal Marines seized an Iranian tanker off the coast of Gibraltar earlier this month as the UK claimed the vessel had violated sanctions on Syria.
An audio recording has emerged of communications between Iranian authorities and HMS Montrose moments before the Stena Impero was seized in a busy oil shipping route.
In the radio recording, the Iranian vessel can be heard saying: "If you obey, you will be safe.
"Alter your course immediately.
"I want to inspect the ship for security reasons."
HMS Montrose replied: "You must not impair, impede, obstruct or hamper the passage of the Stena Impero.
"Please confirm that you are not intending to violate international law by attempting to board."
Iran has directly linked the seizure of the vessel with Britain's role in detaining a tanker carrying Iranian oil earlier this month.
A spokesman for Iran's Guardian Council was quoted as saying "the rule of reciprocal action is well known in international law" and that Tehran made the right decision in the face of an "illegitimate economic war and seizure of oil tankers".
The explanation, which contrasts with a suggestion on Friday night that the Stena Impero was "violating international maritime rules" and had collided with a fishing boat, came as the UK Government warned British ships to stay away from the Strait of Hormuz.
HMS Montrose, which is patrolling the Persian Gulf to protect shipping, and earlier this month intercepted Iranian patrol boats surrounding another UK-flagged tanker, reportedly arrived minutes too late to prevent the latest incident.
A second oil tanker, the Liberian-flagged Mesdar, which is managed by Norbulk Shipping UK, veered off course towards the Iranian coast after it was boarded by armed guards at about on Friday.
Communication with the ship was later re-established and the crew were unharmed.
The tanker was reportedly allowed to resume navigation.
France and Germany joined condemnation of Iran's actions, which have triggered concerns that it will lead to further oil price hikes amid heightened tensions in the Gulf involving Iran, the US and UK.
Hostilities between Iran and the West, mainly the US, have increased after Washington imposed new, tighter sanctions in May.
The sanctions were introduced after President Donald Trump pulled out of a nuclear deal signed by his predecessor Barack Obama.
The deal had provided Iran access to world trade in return for curbs on its nuclear programme.
In recent weeks, the US has accused Iran of seizing several oil tankers in the region, and the Americans and Iranians have shot down each other's drones.
Britain became involved when the Royal Marines seized an Iranian tanker off the coast of Gibraltar earlier this month as the UK claimed the vessel had violated sanctions on Syria.
The crisis between Iran and the US escalated on Monday as Tehran claimed it had and some have been sentenced to death.
An intelligence ministry official claims CIA operatives infiltrated "sensitive" and "vital" sectors of Iran - including economic, nuclear, military and cyber sectors - to steal secrets.
Some of those involved in the spy ring were sentenced to execution for being "corrupters", the ministry added.
