Thailand's senate has began debating a hotly-contested political amnesty bill as an estimated 15,000 anti-government protesters gathered in Bangkok.
The senate was due to vote on the bill on Monday. If, as expected, it rejects the legislation it is likely to embolden a range of anti-government forces who have massed on Bangkok's streets for nearly a fortnight.
Critics say the bill has been crafted to pave the way for a return of the polarising ex-Prime Minister Thaksin Shinawatra, who is the current Prime Minister Yingluck Shinawatra's brother.
"This bill violates the rule of law. All laws must be equal for everyone," said Senator Manoj Kraiwong, echoing the views of several speakers in the televised debate.
The opposition Democrat Party has harnessed the growing anti-government sentiment.
|Thousands demonstrated against the bill in Bangkok on Sunday
It was holding a anti-amnesty rally on Monday evening - before the expected vote by the senate - which it said could draw tens of thousands to the city's political centre, heightening fears of clashes with police.
A Democrat lawmaker Akanat Promphan said the protesters would give the government a "deadline" of 6pm (11:00GMT) to kill the bill before taking further - as yet unspecified - actions.
Thousands of police were deployed across Bangkok to keep the peace, including nearly 7,000 officers around the parliament and the prime minister's office.
Since it was passed by the lower house on November 1, the bill has set off daily demonstrations and raised fears of reviving political turmoil that has convulsed the country since Thaksin was toppled by a coup in 2006.
Opponents of the amnesty say the legislation is intended to whitewash Thaksin's alleged crimes and allow him to return to Thailand without going to jail.
Thaksin fled into exile to avoid serving a two-year prison term for corruption.