US Deputy Secretary of State William Burns held talks with Prime Minister Nuri al-Maliki on Saturday at a time of a festering political standoff in Iraq, officials said.
The visit, along with one by US Central Command chief General James Mattis, comes less than a month after American forces ended a pullout from Iraq, leaving behind a row between the Shiite-led government and the main Sunni-backed bloc.
He "consulted with Iraqi leaders on a range of critical issues of mutual interest, including regional developments, bolstering our bilateral relationship ... and the political situation," a US embassy spokesman said.
Maliki's office said the premier met with Burns and Mattis.
Burns later held talks with parliament speaker Osama al-Nujaifi, the speaker's office said.
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He was also to meet with President Jalal Talabani, Foreign Minister Hoshyar Zebari, National Security Adviser Falah al-Fayadh, and Iyad Allawi, head of the mostly Sunni-backed Iraqiya bloc.
The senior diplomat is to visit the Kurdish regional capital Arbil in northern Iraq for talks with Kurdish president Massud Barzani.
Burns's visit comes amid a festering row in Iraq that erupted the day before US forces completed pullout on December 18.
Authorities have charged Vice President Tareq al-Hashemi, a Sunni Arab, with running a death squad and Maliki, a Shiite, has called for his Sunni deputy, Saleh al-Mutlak, to be sacked after the latter called the premier a dictator.
Hashemi and Mutlak's Iraqiya bloc has largely boycotted parliament and cabinet, and Hashemi, who denies the accusations, remains holed up in the Kurdish region which has not handed him over to Baghdad for trial.
The crisis has stoked sectarian tensions, with insurgents having carried out three deadly sets of attacks since the row broke out that have killed nearly 200 people in total.
On Saturday, a suicide bomber killed 53 people on the outskirts of the southern city of Basra.