Bangkok, Thailand (CNN) -- Thailand braced for anti-government demonstrations that began Friday and were expected to peak over the weekend with as many as 150,000 protesters on the streets.
In anticipation, the government has mobilized 50,000 security forces, said acting spokesman Panitan Wattanayakorn.
The mass rallies are expected to be peaceful but Army spokesman Col. Sansern Kaewkumnerd said that crowd-control measures will be used if necessary.
"We will exercise the most effort to explain to demonstrators not to resort to violence, but if worse comes to worst, we may have to apply tear gas," he said.
The "red shirt" opposition protesters include supporters of former Prime Minister Thaksin Shinawatra, who was ousted in a bloodless military coup in 2006. Thaksin was the only Thai prime minister to serve a full-term in office and remains hugely popular.
The protesters say that current Prime Minister Abhisit Vejjajiva was not democratically elected and have demanded that he call new elections.
Since Thaksin's ouster, Thailand has endured widespread political unrest that has pitted Thaksin loyalists against Abhisit's supporters. In September, tens of thousands of red shirt demonstrators converged on the Thai capital, Bangkok, to mark the third anniversary of the coup that ousted Thaksin.
CNN's Kocha Olarn contributed to this story