President Jalal Talabani Thursday vowed there would be no amnesty for the killers of Iraqis after the discovery of 60 corpses found in an Iraqi river, which he said were of Shiite hostages seized in a kidnap drama so far shrouded in mystery.

And while insurgents appeared to be stepping up their attacks, there was still no breakthrough in talks to form a government which have dragged on since a Shiite-led alliance swept the January 30 elections.

The latest attacks brought to at least 10 the number of foreign security specialists killed in Iraq over the last two days.

A US Embassy spokesman said 11 people were killed in the Bulgarian helicopter crash, among them six Americans, three Bulgarians and two people identified as Filipinos by the Bulgarian defence ministry in Sofia.

However, the Canadian company operating the aircraft, SkyLink, said two of the victims were Fijian security guards, not Filipinos.

"SkyLink is often chartered for transporting people around the country," the embassy spokesman said.

The six US citizens worked for Blackwater Security Consulting, which provides security for the embassy and other clients, the spokesman said.

Iraq insurgents downed the Mi-8 helicopter with a missile, the Bulgarian defence ministry said.

The Islamic Army in Iraq claimed the attack, releasing on the Internet a video showing what it said was wreckage of the stricken aircraft and the corpses of victims.

The three-minute video showed the debris of the helicopter in flames as well as the burned-out corpses. The group also claimed to have captured and executed one of the victims.

Another American working for Blackwater was killed near Ramadi when a roadside bomb blew up near his vehicle.

Earlier, one employee from the British-based Aegis defence services company was killed and another injured when a bomb exploded as their car headed from the capital towards the airport, company spokeswoman Sarah Pearson said.

"Aegis defence services ltd. can confirm that one member of staff was killed in the line of duty in Baghdad today and another person sustained injuries," she said. She gave no details as to their identities.

One Iraqi civilian, travelling in another car, was also hurt by the blast, according to an interior ministry official.

Thursday's attack followed an ambush on the same road Wednesday, when an American, an Australian and a Canadian security specialist were killed when vehicles in their convoy came under small arms fire, their employer, the British-based Edinburgh Risk security firm said.

Thousands of security specialists, mostly former soldiers, currently work in Iraq, helping to protect coalition facilities along with employees of private organisations and foreign news teams.

In other developments, US troops shot and killed an Iraqi woman they said had set off a roadside bomb under a military convoy, wounding one soldier near the restive city of Ramadi, about 100 kilometers (60 miles) west of Baghdad.

Meanwhile, an Iraqi interpreter working in the green zone, a protected area which is home to parliament, the government and the US embassy, was kidnapped Thursday by armed men who grabbed him in a taxi, an interior ministry official said.

Two US marines died in a bomb blast in the volatile western Iraqi city of Ramadi on Wednesday, the US military said in a statement.

And militants loyal to Al-Qaeda frontman Abu Musab al-Zarqawi claimed in an Internet statement responsibility for attempting to assassinate Prime Minister Iyad Allawi on Wednesday.

A car bomb targeting Allawi's motorcade killed two policemen. This was the fifth attempt on the prime minister's life.

Talabani suggested the bodies fished out of the river Tigris, some 40 kilometers (25 miles) south of the capital, were those of Shiite hostages recently seized by Sunni insurgents in Madain, a few miles upstream.

He vowed in an address to the nation that there would be no pardon for insurgents whose hands were "stained with the blood of Iraqi people".

Top government officials, including the interior minister, have denied there was any hostage-taking in Madain and officials said an army raid there on Monday failed to find any evidence of killings.

On Wednesday, police said they had recovered some 60 bodies of men, women and children from the river and riverbanks. The decomposing bodies were immediately buried, police said.

The majority Shiites, who won last January's elections, and the second-placed Kurds are currently negotiating to form a government with Allawi's coalition and the Sunnis, many of whom boycotted the elections and are accused of providing the backbone to the insurgency.

Talabani told the Turkish CNN-Turk channel that a cabinet list could be expected soon but added that there were still differences between the would-be government partners on the allocation of some cabinet posts.

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