About 30,000 protesters continued to occupy the prime minister's compound in central Bangkok, forcing Samak and his advisers to work out of a military command post on the outskirts of the city.
The protests are part of efforts by an umbrella group of anti-government activists to bring three months of street demonstrations to a conclusive climax. The group, the People's Alliance for Democracy, has strong ties to members of Thailand's elite and has been holding almost daily street protests since May 25. They are demanding the government's resignation, accusing Samak and his allies of being proxies of Thaksin Shinawatra, the billionaire tycoon turned politician who was removed as prime minister two years ago in a military coup and who is now in Britain reportedly seeking political asylum.
Calls by the People's Alliance for wider participation in their movement bore some fruit Friday, with two major labor unions representing railroad workers and employees of Thai Airways, the national carrier, calling for partial strikes. About 35 trains between Bangkok and the provinces were canceled.
Images broadcast on Thai television showed groups of protesters raiding the tarmac of the airport on the resort island of Phuket as bewildered tourists looked on, causing the cancelation or diversion of 16 flights. Protesters also blocked the entrance of the airports in Krabi and Hat Yai, two other tourist destinations in southern Thailand.
Samak and his government have shown what many analysts say is notable restraint in dealing with the protesters. The occupation of the government compound has prevented civil servants working in the prime minister's office from coming to work since Tuesday and has shut down a number of schools and offices in the area.
"I am the one who ordered the police to step back," Samak said Friday. "I promised people in this country that I would be soft and gentle," he said. "I've been patient up until now. But others may not be as patient."
The police responded forcefully Friday to protesters who approached the gates of the metropolitan police headquarters, firing tear gas into the crowd that marched beside a truck emblazoned with a sign in Thai saying, "This evil government must get out."
Sondhi Limthongkul, one of the leaders of the protests, vowed to continue occupying the prime minister's compound until the government stepped down.
The police issued arrest warrants for Sondhi and eight other protests leaders on charges of insurrection, conspiracy, illegal assembly and refusing orders to disperse.
Samak said Friday he would consider declaring a state of emergency but only if the situation worsened considerably.