The Palestinian Authority condemned on Saturday Britain's designation of the Hamas movement as a terrorist organization.
The move is an "unjustified attack" against the Palestinian people that will force it to review its relations with London and role in the region and peace process, it said.
Britain's interior minister Priti Patel on Friday said she had banned Hamas in a move that brings the UK's stance on Gaza's rulers in line with the United States and the European Union.
"Hamas has significant terrorist capability, including access to extensive and sophisticated weaponry, as well as terrorist training facilities," Patel said in a statement.
The organization will be banned under the Terrorism Act and that anyone expressing support for Hamas, flying its flag or arranging meetings for the organization would be in breach of the law, the interior ministry confirmed.
Patel is expected to present the change to parliament next week.
The Palestinian foreign ministry condemned the designation, saying it was an "unjustified attack against the Palestinian people, who are suffering from the ugliest forms of occupation and oppression."
In a statement, it said that by taking such a move, the British government has placed obstacles in achieving peace, consolidating calm and reconstructing the Gaza Strip.
It noted that the move took place a week after Israeli Prime Minister Naftali Bennett met his British counterpart Boris Johnson on the sidelines of the Glasgow climate summit to urge him to blacklist Hamas.
Moreover, it noted that Patel is sympathetic with Israel, citing her visit years ago to Israeli settlements in the Golan Heights without first receiving the approval of her government.
This time around, the designation has received government backing, in a "dangerous shift in traditional British policy towards the Palestinian-Israeli conflict," added the foreign ministry.
It called on London to reverse its decision, saying it will continue to assess the impact the designation will have on Palestinian-British relations.
Hamas had condemned the designation, saying it was a sign of bias towards Israel and a violation of international laws that permit the resistance of occupation.
All Palestinian factions on Saturday announced the launch of a national conference against Britain and its designation, warning of the consequences of the move.
They called on London to reverse its decision.
In a statement after their emergency meeting, they said all Palestinian people are "united" in rejecting the designation.
A representative of the Fatah movement said Hamas was a "main component of the Palestinian fabric and national Palestinian liberation efforts."
"The Palestinian people will not allow any side to harm one of its main elements," he added.
He called on all sympathizers with the Palestinian people, the world over, the United Nations, Arab League and other organizations to reject the British move and firmly confront it.
