Sadr arrived at Arbil airport on a private plane from Tehran, and was met by the region's president Massud Barzani and other Kurdistan officials, an AFP reporter said.

"It is a historic visit, and it will lead to the expansion and strengthening of the relationship between Kurdistan and all Iraq," Fuad Hussein, the head of the office of the presidency in Kurdistan, told journalists at the airport.

"It will also lead to more stability in the political situation in the country," he said.

Sadr, who spends most of his time on religious studies in Iran, "will meet Barzani today, and there is a significant possibility that he will go to Najaf after finishing his meetings in Kurdistan," a source in Sadr's office in Najaf told AFP.

Sadr's spokesman Salah al-Obeidi had earlier told a news conference in Baghdad that the cleric had accepted an invitation to visit Kurdistan, saying that "the crisis needs such a move to resolve the situation."

He added that "the sayyid (Sadr) is trying to put Al-Ahrar (his parliamentary bloc) and himself personally in the middle."

"One of the goals of the visit is to solve the crisis," Obeidi said.

Tensions remain high between Kurdistan and Baghdad, especially between Barzani and Prime Minister Nuri al-Maliki.

Barzani said on April 22 that he opposes the sale of F-16 warplanes to Iraq while Maliki is premier, as as he fears they would be used against Kurdistan.

Barzani had previously accused Maliki of moving toward dictatorship, and said the premier aimed to "kill the democratic process" after the head of Iraq's electoral commission was arrested for alleged corruption.

Earlier this month, Kurdistan stopped oil exports over more than $1.5 billion (1.13 billion euros) it said is owed to foreign oil companies working in the region, that Baghdad has allegedly withheld.

The central government's top two oil officials responded by saying Arbil owed Baghdad more than $5 billion in promised exports, and was smuggling the oil it produced to Iran.