Labour faces a showdown next year with a delegation of Caribbean nations set to submit new reparations demands to Britain.
The 15 member states of the Caribbean Community (Caricom) have previously set out its formal demands in a 10-point plan detailing what form slavery reparations should take, from apologies to payments and debt cancellations.
But a Caricom delegation to the UK is now being planned for 2025 with an updated list of demands.
David Lammy’s Foreign Office staff may even have to receive the delegation for reasons of protocol, it is understood.
Various sums have been demanded by Caribbean nations, with some estimates from academics and lawyers ranging from £206 billion to £19 trillion.
Arley Gill, a lawyer and the leader of Grenada’s national committee for reparations, said: “The time has come for the British Government and Prime Minister Starmer to sit down with the leaders of those countries where these crimes against humanity were committed, and begin to have an engagement on how best to go forward with reparatory justice.”
He added that leading advocates were looking to seek an audience with Mr Lammy and other members of the British Government.
It comes as Sir Keir Starmer prepares to face down demands for reparations to former colonies when he attends the Commonwealth Heads of Government Meeting in Samoa this week.
The planning of the 2025 delegation is in its early stages.
But leading Caribbean campaigners have restated their demands, and called on Mr Lammy directly to back the cause of reparations which he has signalled support for in the past.
Sir Hilary Beckles, the chairman of the Caribbean Community (Caricom) reparations commission, said the Foreign Secretary should have a “free hand” on the issue of compensation, and called him a “supporter of the discourse” on reparations.