Rebels blamed

Mohammed al-Qadhi, a journalist from The National in the capital, Sanaa, told Al Jazeera that there were conflicting reports on how many bodies had been found.

He said some local media reported that "all hostages were killed by unidentified kidnappers".

There was no immediate claim of responsibility for the abductions, but officials have blamed a group called al-Huthi.

"The government has accused the al-Huthi rebels, who have been fighting against the government since 2004 in Saada," al-Qadhi said.

"[Al-Huthi] considers this just a prelude from the government to launch another attack against them.

Killings 'unprecedented'

"I have spoken to the spokesman of the rebel leader and he told me they strongly condemned this attack which is actually unprecedented in the history of kidnappings in Yemen."

A tribal leader in the area put the blame on al-Qaeda.

Kidnappings of foreign tourists or workers are fairly common in Yemen but most incidents are resolved peacefully in exchange for ransom or concessions from authorities.

In Berlin, the foreign ministry said it could not confirm the reports that Germans had been killed.

A spokesman said a ministry crisis team and the German embassy in Sanaa were trying to get more details.

Yemeni tribesmen in Saada on Friday released a group of 24 doctors and nurses whom they abducted a day earlier, demanding the authorities release two prisoners.