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BAGHDAD - Iraqi Deputy Prime Minister Salam al-Zobaie has undergone surgery after being wounded when a suicide bomber blew himself up in a hall where he was attending prayers today.

Officials said at least six members of Zobaie's entourage were killed in the second assassination bid on a senior member of the US-backed government in a month.

One of Zobaie's aides named the suicide bomber as Wahab Saadi, one of the deputy prime minister's own guards.

"He's wounded but it's not serious," an official in Prime Minister Nuri al-Maliki's office told Reuters after Maliki visited Zobaie at the US military hospital in Baghdad's international Green Zone.

In the south, Iranian forces seized 15 British Royal Navy personnel, Britain said, triggering a diplomatic crisis and pushing oil prices above US$62 a barrel to a three-month high.

"This is just the kind of scenario we've worried about with all these military assets operating so close together," said John Kilduff, senior vice president for energy risk management at Fimat USA.

Britain said the incident took place in Iraqi waters, where it routinely boards merchant vessels with UN permission to search them. The Foreign Office summoned Iran's ambassador and demanded the immediate, safe release of the personnel.

Brigadier-General Qassim Moussawi, spokesman for security in Baghdad, told Iraqiya state television Zobaie was wounded in various parts of his body and underwent surgery.

An aide to Zobaie said the deputy prime minister was hit by shrapnel in the abdomen and shoulder and that two of his brothers were among those wounded or killed.

The high-profile attack came the day after a rocket landed yards from the prime minister's home during a news conference with the United Nations secretary general.

Moussawi said Zobaie was the target of two co-ordinated attacks -- the suicide bomber at a prayer hall in the compound of his residence and a car bomb at his home. He said six of Zobaie's security guards were killed and 15 people wounded.

Zobaie, one of two deputy prime ministers, is a member of the Accordance Front, the main Sunni Arab grouping in Iraq's Shi'ite-led national unity government.

He is also a member of a well-known tribe from the Abu Ghraib area northwest of Baghdad.

The aide said rival factions in the tribe were feuding, one side supporting al Qaeda militants and the other loyal to the deputy prime minister and the government.

The western province of Anbar has recently seen a surge in violence between tribes who have come out against al Qaeda and militants who have been taking revenge on them for doing so.

Insurgents have frequently targeted leaders of the US- backed government. Last month Iraq's Shi'ite vice president, Adel Abdul-Mahdi, was wounded by shrapnel when a bomb killed six people inside the Public Works Ministry.

Iraqi and US security forces are engaged in a major security crackdown in Baghdad aimed at stemming sectarian violence that threatens to pitch the country into civil war.

The attack was not prevented by a four-hour vehicle curfew that is imposed every Friday in an attempt to stop car bombs on the Muslim holy day when people gather for prayer.