US Vice President Joe Biden called Turkish Prime Minister Recep Tayyip Erdogan to discuss regional security, including Iraq's political crisis, the White House said Thursday.

The call followed up on Biden's visit to Turkey in December, and included an undertaking to work to support the rule of law and encourage democracy in the region, the White House said in a statement.

The two men spoke after the latest explosion of violence in Iraq, in which attacks against Shiite Muslims killed at least 68 people on Thursday, the worst toll in nearly five months.

Biden was put in charge by President Barack Obama of US dialogue with Iraq which helped piece together a fragile governing coalition and led to the withdrawal of all US troops from the country last month.

The Obama administration has carved out a close relationship with Turkey, and worked on issues including the Syrian crackdown on anti-government protests, Iran's nuclear challenge and Ankara's struggle with PKK Kurdish rebels.

Washington has also been dismayed by the tension between Turkey and its other key Middle Eastern ally Israel.