Tens of thousands of anti-government protesters aiming to shut down central Bangkok took over key road junctions.

Seven rallies at the intersections halted much of the traffic into the capital's business district as part of a campaign to thwart elections and overthrow the government of Shinluck Shinawatra.

The intensified protests were peaceful as people sporting Shutdown Bangkok T-shirts blew whistles, waved flags and spread out picnic mats to eat on the pavement.

The government deployed 10,000 police along with 8,000 soldiers at government offices.

Protesters have said they plan to surround ministries to prevent them from functioning and have threatened to cut utilities to the private residences of the prime minister and her cabinet colleagues.

Most schools in Bangkok were closed, as was at least one shopping mall.

Foreign Minister Surapong Tovichakchaikul said on Sunday: "We don't want confrontation with the protesters.

"In some places we will let them into government buildings."

Still, the protests raise the stakes in a crisis that has killed at least eight people in the last two months and fuelled fears of a possible army coup.

Army commander General Prayuth Chan-ocha has repeatedly said he wants to stay out of the conflict but late last month he refused to rule out the possibility of a military takeover.

The confrontation broadly pits the urban middle and upper-class opponents of the government against its supporters in the poorer countryside.

The posh protesters are demanding the administration is replaced by a non-elected "people's council."

The opposition has said it will boycott the Febrary 2 election, possibly because the government would almost certainly win it.

Candlelit vigils have been held to counter the shutdown and urge that the election be held.

Pro-government rallies have been held outside the capital but government supporters have so far avoided confrontation in the streets of Bangkok.

Overnight a gunman opened fire on protesters camped near a government complex, shooting one man in the neck.

And in a separate incident a gunman fired about 10 shots at the headquarters of the opposition Democrat Party, shattering windows but causing no casualties.