Sinn Fein leaders are due to hold Brexit talks with Jeremy Corbyn later on a day of meetings in London.
Party president Mary Lou McDonald and vice-president Michelle O’Neill are also set for discussions with Northern Ireland Secretary Karen Bradley.
They will also meet a number of SNP MPs at Westminster.
On Sunday, Mrs McDonald said she would tell the Labour leader that Irish interests must be protected whatever the outcome of his Brexit negotiations with Prime Minister Theresa May.
Mr Corbyn is due to meet the republican leaders late this afternoon.
“We will set out again the very clear need to protect Irish interests and make it very, very clear that whatever way Brexit lands, deal or no deal, that Irish interests have to be protected,” said Mrs McDonald.
“Our peace process, our all-Ireland economy, crucially our citizens’ rights, cannot be the collateral damage to the Tory Brexit.”
At the weekend, Mrs McDonald also confirmed that Sinn Fein will hold a convention this weekend to select a candidate to fight a potential European election in Northern Ireland.
“If an election happens, we will fight the election,” she said.
“We are ready.”