David Cameron will be questioned by MPs about the government's response to the Ukraine crisis and the actions of Russian president Vladimir Putin.
The prime minister's appearance at the Liaison Committee follows the "sham" referendums in eastern Ukraine which led to separatists in the Donetsk region declaring an independent state and asking to join Russia.
The West has refused to recognise the results of the referendums in Donetsk and neighbouring Luhansk, with European Union foreign affairs chief Baroness Ashton describing them as "illegitimate and illegal".
The EU has responded to the latest developments in Ukraine by widening existing travel bans and asset freezes to a further 13 individuals as well as two firms based in Crimea, which was effectively annexed by Moscow.
Foreign Secretary William Hague has warned Russia it must allow planned elections to go ahead unimpeded if it wants to avoid more damaging EU economic sanctions.
EU governments will now wait to see if Russia respects the Ukrainian presidential election - set by the government in Kiev for May 25 - before deciding whether to move to more far-reaching economic sanctions.
"It is the attitude and behaviour of all parties, including Russia, towards the holding of the elections on May 25 that will be a major determinant of whether such sanctions are necessary," Hague said.
Defence Secretary Philip Hammond told the Commons that the government was considering a request for equipment from the Ukrainian military and acknowledged that Mr Putin's actions would influence the thinking behind the next defence spending review.
He told MPs: "We have received a request for additional equipment from the Ukrainian armed forces and we are considering carefully how to respond to that request at the moment."
He added: "Some might suggest our eyes have wandered away from the potential challenge from Russia, a militarily very powerful nation with which we do not always enjoy alignment of interest.
"I think the consequences of this crisis will be to focus Nato member states very clearly back on the potential challenge from Russia, amongst other challenges Nato has to be prepared to deal with in the future."
Hammond dismissed the eastern Ukraine referendums as a "sham and a farce".
As well as events in Ukraine, Cameron will also face questions from senior MPs about the war in Syria - another crisis zone where Russia has had a significant influence.
The Liaison Committee, made up of MPs who chair parliament's other select committees, will also question Cameron about immigration and his goal of cutting net migration to the "tens of thousands".