Baghdad - US Secretary of Defence Robert Gates and the president of Iraq's Kurdish Autonomous Region, Massoud Barzani, discussed on Wednesday how the United States might help mediate disputes between Iraqi Kurds and Arabs over land and oil, a spokesman for Barzani said.

The two "discussed bilateral relations between the (Kurdish) region and Washington, in addition to the US role in solving pending issues between Baghdad and Arbil," Fouad Hussein, Barzani's chief of staff, told Baghdad's Aswat al-Iraq news agency.

The Kurdish regional government in Arbil and the central Iraqi government in Baghdad both claim land and hydrocarbon resources bordering the semi-autonomous Kurdish region.

"Probably our number one driver of instability is Arab-Kurd tensions," said General Ray Odierno, the head of US forces in Iraq. "We think that many of the insurgent groups are trying to exploit the Kurd-Arab tensions in the north."

The Kurdish parliament last month passed a draft constitution that defined the borders of Kurdistan as including land that now falls in the provinces of Diyala, Nineveh, and al-Ta'mim, the site of the city of Kirkuk and nearby oil fields worth millions.

Kurdish voters had been scheduled to put the draft to referendum on Saturday, but the parliament indefinitely postponed the referendum in an extraordinary session on July 9, following pressure from Baghdad and Washington.

As Gates and Barzani discussed the status of Kirkuk, police there said they had arrested a man on charges of smuggling Katyusha rockets into the city.

Shirzad Mofiri, the head of Kirkuk's al-Uruba police station, told the German Press Agency dpa that police had found a Katyusha rocket and other explosives in the man's house, and that he had confessed to smuggling missiles to Baathist insurgents in the city.

The Baathists used the missiles to attack the Kiwan military base west of Kirkuk, sometimes missing their mark and hitting nearby residential neighbourhoods, Mofiri said.

In Baghdad, some 250 kilometres to the south, police intercepted a man riding a bicycle laden with explosives near a crowded market, Hatem Aziz, head of police for the northern Baghdad district of al- Taji, told dpa.

"When the man was arrested, he confessed that he intended to detonate the bomb in the market," Aziz said.

In a separate development, Iraq's Ministry of Interior said in a statement that police had defused another bomb found in the Baghdad neighbourhood of al-Dawra.

Gates arrived in Iraq on Tuesday in an unscheduled visit after stops in Israel and Jordan. On Tuesday he met with Prime Minister Nuri al-Maliki and with Iraqi and US forces at the joint US-Iraqi military base at Talil, near the southern Iraqi city of al-Nasseriya. (dpa)