by Dave Clark and Olivier Knox Wed May 9, 1:20 PM ET

BAGHDAD (AFP) - A deadly bomb attack in a once safe Kurdish city and a rocket blast in Baghdad's Green Zone served as a violent backdrop Wednesday to a surprise Iraq visit by US Vice President Dick Cheney.

Cheney arrived in the war-torn capital to meet senior Iraqi leaders just as a new poll revealed that 59 percent of American voters want the White House to to set a timetable for withdrawing US troops from Iraq.

The vice-president brought Prime Minister Nuri al-Maliki the message that Washington's patience with the slow pace of Iraq's political peace process is running out, even as new attacks further undermined its progress.

A powerful bomb exploded in front of the regional interior ministry in Arbil, the capital of northern Iraq's autonomous Kurdish region, an area that has been spared the worst of Iraq's descent into sectarian bloodshed.

The blast tore a two metre (yard) deep crater in front of the ministry, and scattered the bodies of dead and injured outside the heavily guarded building.

Kurdistan's health minister, Zirian Abdelrahman, said 19 were people killed, although his colleague at the interior ministry later gave a lower toll.

"It was a truck bomb carrying cleaning products that targeted our ministry and killed 14 people and wounded 87, including government employees," regional interior minister Karim Sinajri told journalists.

While insurgent car and truck bombings are an almost daily scourge in central Iraq, this was a rare incident in the Kurdish region, and a blow to its campaign to portray itself as an investor-friendly haven of calm.

In Baghdad, a rocket exploded near the US embassy in the fortified Green Zone during Cheney's visit, an Iraqi defence official said.

Smoke could be seen rising near the US compound shortly after the blast, which was heard at around 6:15 pm (1415 GMT). The Iraqi official, who spoke on condition of anonymity, could not say if there were any casualties.

Cheney's movements during his visit were kept secret for security reasons, but the vice president later confirmed at at a press conference that "I spent today here basically in our embassy and military headquarters."

Reporters covering Cheney's trip to Iraq were ushered from their workspace here after hearing a muffled boom that rattled the windows.

A spokeswoman for Cheney, Lea Anne McBride, said "his meeting was not disrupted and he was not moved" as a result of the explosion.

Last Thursday, four Asian contractors working for the US embassy were killed in a rocket attack.

Insurgent and militia groups opposed to the ongoing US troop presence in Iraq regularly fire rockets and mortars into the Green Zone, a walled city district that houses the US embassy and Iraqi government.

Elsewhere in the city a high-ranking official in the housing ministry was assassinated and a construction worker building a controversial wall around the Sunni neighbourhood of Adhamiyah was shot dead.

US military spokesman Major General William Caldwell told reporters that after dropping by two-thirds due to a massive security operation in the capital, assassinations and executions were on the rise again.

"There has been a slight uptick in the last two weeks in the number of murders and executions observed in Baghdad," he said.

Both the Iraqi and US commands refuse to reveal the figures upon which they base such reports. An interior ministry official, speaking on condition of anonymity told AFP that 25 bodies were found on Tuesday alone.

In the central Iraqi city of Samarra, Sunni insurgents destroyed two police stations belonging to the Shiite-led National Police just days after a deadly assault left 12 policemen dead, including their commander.

And in Al-Rashad, northern Iraq, gunmen murdered four journalists working for a US-sponsored weekly that has taken a strong line against terrorism.

Cheney was in Baghdad to warn top Iraqi leaders that US patience with their faltering attempts to reunite Iraq's warring factions is running short.

Shortly after the rocket exploded, and after meeting Maliki and President Jalal Talabani, Cheney told reporters that he had sensed "a greater sense of urgency" among Iraqi officials working to resolve the conflict.

"I did sense, today, a greater awareness on the part of the Iraqi officials I talked to of the importance of their working together to resolve these issues in a timely fashion," he said.

The White House's own sense of urgency will have been fueled by the latest USA Today/Gallup poll, which showed that 59 percent of Americans support setting a deadline for removing US troops from Iraq.

The opposition-controlled US Congress is working on a second bill that would seek to tie future troop funding to some kind of measure of success in Iraq, but President George W. Bush has vowed in advance to veto it.