Thailand faces a crucial week in its long running political crisis, as fears of violence and civil strife have led to calls by senior security officials to tighten security.
Thailand's caretaker government says it is stepping up security to prevent clashes between pro- and anti-government protests.
Political tensions are rising amid anti-government calls for a neutral prime minister to be appointed.
Department of Special Investigation chief Tharit Pengdit says calls for a non-elected head of government by the anti-government People's Democratic Reform Committee (PDRC) are illegal.
Tharit said the PDRC leader Suthep Thangsuban's calls for a non-elected prime minister are "illegal" and are intensifying conflicts that may lead to violence and even civil war.
Meanwhile, leaders from the pro-government Red Shirt movement made similar warnings of growing social conflict as supporters rallied Saturday, many carrying banners of the image of ousted prime minister, Yingluck Shinawatra.
Yingluck was dismissed along with nine Cabinet members by the constitutional court last week on charges of nepotism. She was replaced by Deputy Premier Niwattumrong Boonsongpaisan.
The government says it hopes to press on with elections scheduled for July 20. February 2 polls were annulled.
The governing Pheu Thai Party, largely under control of former leader Thaksin Shinawatra, hopes to regain the political initiative at the election. Pro-Thaksin parties have won every election since 2001.
But the opposition Democrat Party, which boycotted the earlier vote, is threatening to again stay out without political reforms.
Chulalongkorn University political scientist Panitan Wattanayagorn says the Thai military has stepped up its presence in Bangkok to prevent clashes by the opposing political camps.
Panitan says the political battles are set to escalate over the issues of an appointed prime minister and a Royal decree setting a new election for July 20.
"The legal battles between the two issues will continue for a few days. In the meantime the supporters of the two groups - the Red Shirts and the PDRC - will drum up their supporters and I think the offensive political move will be in the hands of the PDRC, the move more quickly to pressure the Senate to act. But also the aggressive move could be adopted by the Red Shirts trying to occupy other strategic locations," said Panitan.
But reports Sunday said military commanders appeared opposed to Suthep's call for the setting up of an interim government. The army has ruled out a military coup, saying it will only intervene if violence escalates.
Senior advisor to a pro-government Democratic Force Party, Prasaeng Mongkonsiri, says behind the scenes talks may already be underway, including with Thaksin.
"The negotiation is now going on. Not by Khun Niwattumrong probably by Khun Thaksin Shinawatra with some man behind the scene of the PDRC. My personal opinion I believe Khun Thaksin is trying hard to negotiate to find a good solution for the country," said Prasaeng Mongkonsiri.
Thailand's present conflict erupted after Yingluck's government passed a bill granting a general amnesty that would include clearing the way for Thaksin, who has lived in exile to avoid a jail term for corruption, and return home a free man.
But while Thaksin has been strongly supported in the rural areas, he faces opposition in the capital and southern provinces by the urban middle class. He may also have lost support among grass roots backers over failed populist economic policies under Yingluck's government.