Britain has held diplomatic talks with Hayat Tahrir al-Sham, the Islamist group that toppled Bashar al-Assad, despite them being banned in the UK.
Photographs showed senior officials, including the UK's special representative for Syria, Ann Snow, meeting HTS leader Ahmad al-Sharaa, formerly known as Mohammed al-Golani, in Damascus on Monday.
The meeting followed confirmation by Foreign Secretary David Lammy that a delegation had been sent for talks with interim Syrian authorities and civil society groups after the fall of Mr Assad's regime earlier this month.
Mr Lammy told a press conference in London on Monday that the delegation "underlines our commitment to Syria", adding the UK would support an "inclusive transitional political process that is Syrian-led and Syrian owned".
HTS is currently proscribed in the UK as a terrorist organisation.
Iain Dale pushes back against caller who claims Syria will become 'a terrorist superstate'
But Mr al-Sharaa has sought to distance the group from al Qaida and present a more moderate face to the world, leading some to call for the proscription to be removed.
Over the weekend, Mr Lammy said the proscription was no bar to diplomatic contact, after confirmation by US secretary of state Antony Blinken that Washington officials had spoken to the group despite its designation by the state department as a foreign terrorist organisation.
In an interview with international media on Monday, Mr al-Sharaa called for the designation of HTS as a terrorist group to be rescinded, along with sanctions imposed on Syria during the Assad years.
He said: "Syria is very important geostrategically. They should lift all restrictions, which were imposed on the flogger and the victim – the flogger is gone now. This issue is not up for negotiation."
Ex-Middle East adviser: There is 'reason to be cautiously optimistic' regarding situation in Syria
He also sought to ease fears about the new Syria's relationship with Israel, saying he did not want any conflict with Tel Aviv and would not allow the country to be used as a base for attacks.
Meanwhile, Mr Assad said he had not planned to flee Syria as the rebels advanced, but was evacuated by Russian forces after their base came under attack.
In his first public comments since being ousted, Mr Assad said: "At no point during these events did I consider stepping down or seeking refuge, nor was such proposal made by any individual or party."