The situation in Thailand is "very grave" but not bordering on civil war, Australia's foreign minister Stephen Smith says.
Six people were killed when the Thai military stormed the Red Shirt protesters' Bangkok base on Wednesday, and curfews and media blackouts are now in place across about one-third of the country.
But Mr Smith on Thursday told ABC Radio he would not call the situation "civil war".
"I don't want to use a phrase like that," he said.
"But I do want to underline the very grave, difficult circumstances that Thailand's confronted with. The situation had deteriorated significantly in the past week, Mr Smith said.
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"That's why we have changed our travel advice and why we are constantly monitoring the position."
Mr Smith said the latest violence came after years of political turmoil, and the military had done well so far to stay out of the political process.
"We continue to urge restraint, we regret very much the violence that we've seen, the loss of life and the injuries," he said, adding Australia privately and publicly was urging restraint on the part of all sides.
"The last thing that we ... want to see is Thailand revert to military rule and there have been plenty of urgings in recent times for the military to take charge."
Australian citizens are advised not to travel to Bangkok but the airport is safe for transit.
