What are the roots of the crisis?
There is a deep political divide in Thailand - between mostly rural, often poor, supporters of Mr Thaksin, and an urban middle class who object to what they see as his continuing influence in Thai politics.
There have been regular protests by both sides ever since Mr Thaksin was ousted in 2006, but in the past few years the focus has been on the current Thaksin-aligned Pheu Thai government.
The protests began to escalate into violence last November, after the lower house passed a controversial amnesty bill which critics said could allow Mr Thaksin to return from exile without serving time in jail.
The anti-government camp claims that at least 28 people have died since then.
The situation deteriorated still further earlier this month, when a controversial court ruling removed Mr Thaksin's sister Yingluck from her position as prime minister, saying she had acted illegally by moving her national security chief to another position.