Opposition leader Sompong Amornwiwat opened the special session of parliament on Monday with a call for Prime Minister Prayut Chan-o-cha to step down, as anti-government protesters planned to target the German embassy with an unprecedented petition.
The Pheu Thai Party leader said Gen Prayut should step down to show responsibility for the mishandling of the protests by using water cannon against the demonstrators on Oct 16 and issuing a special emergency decree to end their rally outside Government House on Oct 14.
Mr Sompong called for the release of detained protesters as a goodwill gesture to try and end the standoff. The prime minister should be open-minded to the young protesters' demands, and stop delaying the process of writing of a new constitution, he said.
"The prime minister must resign," the opposition leader told the parliament.
The anti-government movement is demanding the immediate release of detained activists and the resignation of the prime minister as the first step towards ending the political crisis.
Palang Pracharath Party MP Paiboon Nititawan defended the prime minister saying the country needed his leadership to get through the economic crisis and to protect the institution of the monarchy, which was under attack by protesters.
But as MPs and senators met in joint session in a bid to move the political conflict off the streets, protesters switched their attention to the German embassy in downtown Bangkok.
They planned to gather at Samyan intersection, near Chulalongkorn University, at 5pm and march to the Germany embassy on Sathorn Road, where they would submit a controversial petition.
A statement on Monday on the Facebook account of the United Front of Thammasat University and Demonstration said the protesters wanted German authorities to look into whether His Majesty the King had violated German sovereignty by exercising his power on German soil.
The rally outside the embassy would show the intention of the protesters, to restore a "truly" constitutional monarchy in Thailand, it said.
It is the first time a foreign government has been targetted by the anti-government protesters.
The Metropolitan Police Bureau has advised motorists to avoid roads in Samyan and the area around the embassy from 3pm onwards.