Thai Prime Minister Samak Sundaravej warned Sunday that anti-government protesters blocking a Bangkok thoroughfare would have to leave, but backed away from threats to forcibly break up the rally.

Samak on Saturday told the nation that he had prepared police and military forces and would bring an end to the week-long anti-government protest.

About 1,200 police, many with shields and batons, gathered in the capital's historic district near the regional United Nations headquarters.

But the tense face-off with about 6,500 protesters from the People's Alliance for Democracy (PAD) ended as night fell with Interior Minister Chalerm Yoobumrung saying there would be no crackdown.

"I never threatened to smash it up," Samak insisted on his regular Sunday morning television address to the nation.

"Police without any batons will go and talk and tell them they cannot do this. Protesters will be asked to move their things from the road -- if not, the police will move it."

He denied there was any threat of violence, but said the protest leaders would have to find another spot that did not block the road.

"Authorities will not make threats or attack them," he said.

"We have no plans to arrest anyone ... The word 'disperse' has never been used, the word 'mob' has never been said. I said the actions (of the protesters) were not right.

"There is no D-day -- police will find the appropriate time to remove them."

About 1,000 protesters remained at the site Sunday morning, police said.

The rally began last Sunday in opposition to Samak's drive to amend Thailand's constitution, written by a military-backed panel after the September 2006 coup, and drew up to 10,000 people.

Protest leaders are now also demanding that Samak -- who won elections last December -- step down, accusing him of acting as a proxy for deposed former prime minister Thaksin Shinawatra.

Two years ago PAD protests against Thaksin led to a coup that ousted him from power, and Saturday's stand-off came amid rumours of a fresh military intervention.

The speculation had grown so intense that the head of the armed forces and the finance minister both had to deny that a putsch was on the horizon.