Russian President Vladimir Putin and U.S. President Barack Obama discussed in a phone conversation the Ukraine crisis and ways of settlement, including Ukrainian President Petro Poroshenko's peace plan, the Kremlin said Monday.

"Putin stressed that a real cessation of hostilities and a start of direct negotiations between the conflicting parties would be of paramount importance to normalize the situation in southeastern Ukraine," the presidential press service said.

"He noted the importance of an immediate resolution of humanitarian issues, including urgent aid to the suffering citizens."

Putin and Obama also expressed serious concern about the deteriorating situation in Iraq. Putin stated his support for Iraq 's struggle to restore peace and security in the country, according to the press service.

The talks also touched upon the situation in Syria, following the complete removal of chemical weapons materials from that country on Monday, as well as the Iranian nuclear program.