Red-shirted protesters have hurled plastic bags filled with their own blood into the residential compound of the Thai prime minister, hoping their shock tactics will bring down his government.

A number of protesters later marshalled in front of the US embassy in a demonstration leaders said would be aimed at exposing the government's alleged illegitimacy to the international community.

Seeking new ways to dramatise their cause, a small group of protesters were allowed by police to approach Abhisit Vejjajiva's walled compound in a ritzy Bangkok neighbourhood and unleash a barrage of bags that smeared the walls, roof and grounds with red.

Earlier, a standoff between protesters and riot police had blocked all approaches to the home of Abhisit, whom the Red Shirt movement hopes to topple by calling for new elections. After negotiations, three dozen demonstrators were allowed to squeeze through the police cordon carrying about six five-litre plastic water bottles filled with blood, which was poured into small plastic bags and then hurled at the home.

The incident in the Sukhumvit Road area, home to many wealthy Thais and expatriates, followed similar "blood sacrifices" a day earlier at Abhisit's office and the headquarters of his Democrat party. The dramatic acts grabbed attention but put the protest movement no closer to its goal of forcing new elections.

The protesters' march and police cordons, thrown up after the government invoked an emergency decree, halted traffic in one direction on Sukhumvit Road, a major thoroughfare, paralysing parts of the neighbourhood. Restaurants closed their doors and residents of luxury buildings were prevented from driving out of the area of Abhisit's house.

Abhisit himself has been sleeping at an army headquarters and taking trips out of the city since the demonstrations began.

"We heard they were coming so I stayed in. Sure enough we're blocked in now," said John Bujnosh, a Texas oil driller who lives on the same street as Abhisit.

More than 100,000 demonstrators from all over the country gathered in Bangkok on Sunday vowing to continue their protest until victory. Abhisit has rejected their demands to dissolve parliament, saying only that he will listen to the protesters and leaving the situation in a stalemate.

Reporters asked one of the protest leaders, Veera Musikapong, what their next move would be. He replied: "I want to know that myself." He said the group made up strategy on a day-by-day basis.

The protesters consist of supporters of former prime minister Thaksin Shinawatra, who was ousted by a 2006 military coup for alleged corruption, and pro-democracy activists who opposed the army takeover. They argue Abhisit came to power illegitimately with the connivance of the military and other parts of the traditional ruling class.

On Tuesday thousands of Red Shirts formed long lines to have their blood drawn by nurses to spill at Government House, the prime minister's office. Leaders claimed to have collected 300 litres.

A few teaspoons of blood were drawn from each volunteer and then transferred into dozens of large plastic water jugs that were passed overhead through the crowd of cheering protesters before being delivered to Government House.

Riot police allowed protest leaders to approach the front gate and pour out the blood, which oozed under the gate as national television broadcast the images live. A purported Brahmin priest in ceremonial robes performed an unorthodox black magic ritual on the Red Shirts' behalf.

"The blood of the common people is mixing together to fight for democracy," a Red Shirt leader, Natthawut Saikua, told cheering supporters. "When Abhisit works in his office he will be reminded that he is sitting on the people's blood." Abhisit has not entered his office at Government House since preliminary protests started on Friday.

Minutes afterwards a government medical cleanup team in white coats, face masks and rubber gloves hosed down the site. Health authorities had warned that the protest risked spreading disease if infected blood splashed bystanders.

Hundreds of protesters then marched and rode pickup trucks and motorcycles to the nearby ruling Democrat party headquarters and splashed several more jugs of blood on the pavement outside.

Surat Horachaikul, a political scientist at Bangkok's Chulalongkorn University, said he believed the protest organisers lacked plans for their next step and that the protests might end in a few days.

"If nothing comes out of this rally the government is likely going to become more stable," he said.

Despite continued anxiety over possible violence, the stock exchange of Thailand and Thai baht currency have remained stable.

Many Bangkok residents, even those sympathetic to the Red Shirt cause, say they are simply tired of the years of turmoil that have hurt the economy.

"I want the protest to stop as soon as possible. My business would be better, I hope," said Suwan Pana-ngham, a downtown food vendor.