Acting Labour leader Harriet Harman has been invited by David Cameron to a high-level security meeting about the threat posed by Islamic State (IS) extremists.
The last time a Labour leader received such an invitation was in 2013.
The government is seeking support to extend the RAF’s air campaign to strikes against IS targets in Syria reports BBC.
Currently, the UK is carrying out air strikes against IS targets in Iraq.
Mr Cameron believes the extremists need to be confronted in Syria too, where the US are conducting operations.
But he is reluctant to ask MPs to vote to extend the RAF campaign unless he has Labour’s backing.
A Number 10 spokesman said: “The PM thought it was important to ensure the leader of the opposition was fully briefed on the current situation.”
Shadow defence secretary Vernon Coaker has also been invited.