"If the caretaker government still refused to comply with the protesters' demand, we would lift the protest to a higher level by blockading the houses of the Prime Minister and important cabinet members. If they still refused to budge, the protesters would take the Prime Minister and cabinet ministers into custody," protest leader Thaugsuban Suthep said.
Firebrand Democrat Party leader, Suthep, who has refused to negotiate with the government, said in the next two to three days, the protesters would lay siege to all government offices.
Suthep is the secretary general of the People's Democratic Reform Committee (PDRC) which is leading the protests.
The protesters want Yingluck to resign to make way for an un-elected "people's council" that would oversee reforms.
Yingluck dissolved Parliament and called snap polls on February 2 but the protesters have rejected to take part in the polls. They want Yingluck and her brother former premier Thaksin Shinawatra out of Thai politics. Thaksin was overthrown in a coup in 2006 and is in self-exile in Dubai.
Demonstrators today surrounded the Customs Department. They stopped officials from going to work at several key ministries. Many key intersections remained blocked here since yesterday.
Meanwhile, Yingluck refused to quit and said, "I've stressed many times I have a duty to act according to my responsibility after the dissolution of Parliament."
"I'd like to say right now I am not holding on (to my position) but I have to keep political stability. I'm doing my duty to preserve democracy."
She also proposed a meeting with her opponents tomorrow to discuss a proposal from the Election Commission to postpone the February vote. But the Democrats and even the Election Commission have refused to take part.
Meanwhile, a PDRC spokesman Aknat Promphan assured that the anti-government would not seize the airport, key transportation systems and the stock market, but would continue demonstrations to pressure Yingluck to resign.