An anti-government protester carries a tent as his group moves from Bangkok's shopping district to Lumpini Park March 1, 2014. The green park in downtown Bangkok was slowly beginning to resemble a tent city on Saturday, a day after anti-government protesters said they would clear camps blocking key intersections and congregate in the park instead. [Photo/Agencies]

Yingluck, who is in northern Thailand, responded that her government wants negotiations, but that the protesters must stop blocking elections and other constitutional processes, and that it was her duty to defend democracy.

Yingluck called early elections soon after the protest picked up steam, but the polls held in early February were disrupted by protesters and remain incomplete. Several districts were holding a re-vote this Sunday. The recent violence led for louder calls for negotiations _ both from inside Thailand and from overseas.

"It's the issue that both of them have to talk about, and today there are several groups who have suggested solutions, as well as other groups who want to take part," the politically powerful army commander, Gen. Prayuth Chan-ocha, said Friday. "Everything must go step-by-step. Whether the military will take part, it depends, but right now, we are playing the role of providing security and protecting the overall stability of the country."

Striking a note of conciliation, Prayuth told reporters: "It's normal for negotiators to have conditions. In every case where there's a conflict, each side has their own conditions, but if they can adjust to one another, then there can be compromise and they can talk, but it cannot be finished in one day."

US Secretary of State John Kerry called for an end to the "politically motivated violence" and urged authorities to investigate the attacks, in which three children died in Bangkok and in eastern Thailand last weekend. Not a single person has been prosecuted for the violence over the last few months.

"The death of several innocent children is particularly horrifying, and must be a last wake-up call to all sides to refrain from violence, exercise restraint, and respect the rule of law," Kerry said in a statement from Washington.

Although the protests have failed to meet several self-proclaimed deadlines for success, pressure has been increasing on Yingluck from other quarters.

She faces several legal challenges that could force her from office, and has to contend with a judiciary which has a record of hostility toward her and her political allies.

Thailand's anti-graft commission on Thursday had her legal representatives hear charges of negligence for allegedly mishandling a government rice subsidy program.

Yingluck could eventually face impeachment by the Senate or criminal charges if the National Anti-Corruption Commission delivers a final ruling against her.