Protesters in Thailand threw bags of blood at Prime Minister Abhisit Vejjajiva's house, in a bid to pressure the government for new elections.  They also demonstrated in front of the United States Embassy, against allegations of sabotage by former Prime Minister Thaksin Shinawatra, who many of the protesters support.

Thousands of anti-government protesters, all dressed in red, massed at the prime minister's house Wednesday, in an upper class neighborhood of Bangkok.

Their trucks and motorcycles temporarily paralyzed traffic, as hundreds of police guarding the home held back the demonstrators.

Security eventually allowed a small group to approach the house and throw plastic bags filled with protesters' donated blood, smearing the walls and grounds red.

The red shirts say the current government, which was chosen by parliament rather than popular vote, is illegitimate.  They want new elections.

It was the second day Thai protesters spilled their own blood.  On Tuesday, they lined up to have a small amount of blood drawn that was later poured onto the government house and the ruling party's headquarters.

The red shirts, as they are known, later blocked traffic outside the U.S. Embassy, as their leaders met with embassy officials.

They were seeking clarification to Thai media allegations that intelligence-sharing uncovered a sabotage plot by former Prime Minister Thaksin Shinawatra, who has been supporting the protests.

U.S. Embassy spokesman Michael Turner says the diplomatic compound accepted a letter from the protesters but would not comment, one way or another, on intelligence.

"We strongly support freedom of speech and peaceful demonstrations are the hallmark of any democratic society," said Turner.  "We continue to call on the protesters and their leaders to not resort to violence and to exercise the right to assemble and protest peacefully in accordance with the law, as they did today. And, we encourage the Royal Thai government to exercise appropriate restraint, as well."

After the brief meeting, a red shirt leader thanked the embassy for supporting democracy in Thailand and the protesters dispersed.

It was the fourth day of large-scale protests in Bangkok by Thais, mainly from the countryside, who say the military and elite have hijacked their democracy.

Many of the red shirts helped elect former Prime Minister Thaksin Shinawatra, who was ousted in a 2006 coup and is in exile to avoid jail for corruption.

The number of protesters has dropped slightly from an estimated peak on Sunday of 100,000 but the red shirts have vowed to keep demonstrating.