BANGKOK — Thousands of anti-government protesters occupied the commercial heart of Thailand’s capital Saturday, forcing the closure of major shopping malls, and said they won’t leave until the prime minister dissolves Parliament and calls new elections.

The government first ordered them out before the end of the day, but as the deadline passed said negotiations would continue today.

It was the fourth weekend demonstration in Bangkok by the mainly poor, rural protesters known as the Red Shirts. They poured into an area of the city lined with upscale hotels and glitzy shopping malls as they groped for tactics to force Prime Minister Abhisit Vejjajiva to meet their demands, after failing to oust his government through peaceful mass marches and negotiations.

More than a half-dozen shopping malls, normally packed with weekend shoppers, as well as office buildings were closed for security reasons as about 10,000 protesters gathered in the area, according to Metropolitan Police spokesman Piya Utayo.

He said the total number of demonstrators, including those in other parts of the city and on the move, reached nearly 55,000.

The government first gave the protesters until 10 a.m. EDT to disperse and sent senior police officers to negotiate. The talks broke down after the Red Shirts refused to leave and police Gen. Panupong Singhara Na Ayuthaya, who headed the negotiating team, said they would resume today.

“If the government wants to arrest us, they would have to arrest every single one of us,” a protest leader, Veera Musikapong, told the crowd, saying they would remain indefinitely. Mobile toilets, food and water began to arrive, some of it brought in from Bangkok’s historic quarter, where the protesters have been camped since March 12.

“Today’s another day when commoners will declare war to bring democracy to the country. There is no end until we win this battle,” another leader, Jatuporn Prompan, said as protesters beat drums and chanted “Dissolve Parliament.”

The Red Shirt movement — known formally as the United Front for Democracy Against Dictatorship — consists largely of supporters of ex-Prime Minister Thaksin Shinawatra and pro-democracy activists who opposed a 2006 military coup which ousted Thaksin.

In a video phone-in Saturday night, Thaksin repeated his calls for the protesters to stay the course.

“Fight and be tired for a few more days. This is better than being tired for the rest of your lives due to injustice,” he said. “I ask that those of you working the next few days to please take days off and join us here. Please be patient. Victory is just around the corner.”

Protest leaders have portrayed the demonstrations as a struggle between Thailand’s impoverished, mainly rural masses — who benefited from Thaksin policies of cheap health care and low-interest village loans — and a Bangkok-based elite impervious to their plight.

Thaksin’s allies won elections in December 2007, but two resulting governments were forced out by court rulings. A parliamentary vote brought Abhisit’s party to power in December 2008. The Red Shirts say his rule is undemocratic and that only new elections can restore integrity to Thai democracy.

Abhisit must call new elections by the end of 2011, and many believe Thaksin’s allies are likely to win — which could spark new protests by Thaksin’s opponents.

The protesters, whose numbers have at times swelled to about 100,000, have received support from lower-middle-class residents, many of them migrants from rural areas, but are detested by many in professional, business and senior government ranks.