Violent demonstrations in tiny Shia-majority country, ruled by a US-backed Sunni-elite, yesterday saw four shot dead, including two protesters, one Bahrani policemen, and a Saudi soldier.

A further six protesters were declared dead after troops overran the demonstrators camp this morning. Observers also observed an armoured personal carrier on the scene with the flag of the UAE.

A doctor spoken to by the UK’s Guardian newspaper said that Saudi troops were preventing staff from leaving the hospital where he worked.

“They are shooting at us, they are shooting,” he said. “Get help, get the international community to help.”

Media reported protesters outside the hospital as chanting “with our blood and our souls we will fight the mercenaries.”

Bahrain’s opposition Shia Wefaq party yesterday issued a statement condemning the arrival of Saudi troops as an assault on the country’s sovereignty.

“We consider the entry of Saudi Arabia or other Gulf forces into the Kingdom of Bahrain’s air, sea or land territories a blatant occupation,” the party said.

Iran, a majority Shia country, waded into the burgeoning conflict when foreign minister Ali Akbar Salehi asked Bahrain not to harm the Shia demonstrators. In response, Bahrain withdrew its ambassador from Tehran in protest.

An Iranian MP, Kazem Jalali, described the Saudi interference as a “criminal” attempt by the US and Saudi Arabia to repress peaceful anti-government protests, pointing to the recent visit of US Defense Secretary Robert Gates to he gulf nation.

There were further signs that the escalating crisis in the 200 year-old monarchy could reignite an ongoing Sunni-Shia feud in the region, after the militant Shia Hezbollah group in Lebanon said that military action against demonstrations would disrupt Bahrain’s already fragile society – 70 percent of the population are Shia, but are largely underrepresented in senior government and political positions.

“Military intervention and the use of violence against a peaceful and popular movement will only complicate matters and eliminate chances of finding a solution,” Hezbollah said.

The UK embassy in the Bahraini capital of Manama closed its doors, while the US – which has substantial military assets in the kingdom, including the US Fifth fleet – ruled out military action.

The UK has closed its embassy in Manama, while the EU and the US have said there is “no military solution” to the crisis. The US maintains its Fifth Fleet in Manama’s port and has significant intelligence interests in the kingdom.

The Formula One grand prix, due to be held in Bahrain this year, has been postponed.