BAGHDAD, Oct 14: Two suicide bombers killed 10 civilians, including four US nationals, on Thursday in one of the bloodiest attacks inside Baghdad's fortified Green Zone, and America's top enemy in Iraq claimed responsibility.

The attacks on a souvenir bazaar and a cafe frequented by US troops and civilians were the first suicide bombings inside what is supposed to be the safest place in Iraq. The country's interim government immediately vowed to strike back.

Officials said 18 people were wounded, including three US military personnel and a US civilian. The blasts, on the eve of Ramazan, occurred within minutes of each other about lunchtime, setting the bazaar alight and gutting a cafe.

"People were screaming. I was on the floor," said Mohammed Nawaf al Obeidi, 25, owner of the nearby Mo's Restaurant, who was at the cafe. "People were stampeding, trying to get out," he said, his right hand bandaged.

The four Americans killed were security staff with a private company on contract to protect the US embassy in Baghdad, a State Department spokesman said, adding that embassy staff had been ordered to remain in the heavily fortified facility until further notice.

The four were killed in the blast in "Vendors Alley", a Green Zone district where peddlers sell souvenirs and handicraft. That blast also seriously injured a fifth US embassy contractor and slightly wounded two State Department employees and an undetermined number of Iraqis.

The six Iraqis were killed in a second attack that occurred in the "Green Zone Cafe". Several Americans and locally hired Iraqis working for the US embassy sustained minor injuries in that explosion.

At the cafe, an orange metal-framed tent built onto a former petrol station, the area was littered with glass, twisted metal, blood and food. Pieces of flesh were lying up to 15 metres away.

Jordanian militant Abu Musab Al Zarqawi's group claimed responsibility for the bombings, a statement on a Web site said. US warplanes struck at targets in Fallujah, killing five people, one of them a 13-year-old boy, and wounding 12. -Agencies