Anti-government protesters on Thursday forced the acting Thai premier Niwatthamrong Boonsongphaisan to flee a meeting hours after a grenade-and-gun attack on their camp left three persons dead even as the army was warned against using force to curb violence.

The protesters stormed into an air force compound — venue of the meeting between Niwatthamrong Boonsongphaisan and the Election Commission to fix a date for new polls — following which the premier fled. They had put off talks at another place on Wednesday due to security fears.

“We are here to tell Niwatthamrong that there is no point standing in our way,” Chumpol Jumsai, an anti-government leader, said from the top of a truck to hundreds of protesters.

Concerned by the spurt in violence, Army Chief General Prayut Chan-O-Cha warned that the military may “use force” if political violence escalated.

“If violence continues, the military may need to come out... to restore peace and order,” he said in a rare official statement, adding his troops “may need to use force to resolve the situation”.

The fresh unrest casts doubts on the July 20 polls, with the EC saying the elections “must be postponed” due to prevailing political unrest that has claimed 28 lives.

EC member Somchai Srisutthiyakorn said an election on July 20 looked improbable.

“We may have to push back the polls,” he said.

Earlier, at least three persons were killed and 24 others injured in the latest attack in which grenades were hurled at anti-government People’s Democratic Reform Committee (PDRC) members. Following the explosion, people in a pickup truck opened fire, according to witnesses.

The PDRC has launched its “all-out final battle” to install an unelected leader after Yingluck Shinawatra, Thailand’s only woman premier, was ordered to step down by the Constitutional Court over abuse of power.

Another court indicted her for negligence over a controversial rice subsidy scheme and Ms. Yingluck will face impeachment that could see her banned from politics for five years.

The two court decisions have bolstered the opposition that has been demanding Ms. Yingluck’s ouster for months and accuse the 46-year-old of acting as a proxy for her fugitive brother, former premier Thaksin, who was ousted in a coup in 2006.

The EC and Yingluck-led government earlier reached an agreement to hold elections on July 20 after the February 2 snap polls were declared null and void.

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