Puea Thai Party sources said Yingluck left Thailand last week and flew via Singapore to Dubai where her brother, former Prime Minister Thaksin Shinawatra, who lives in self-imposed exile to avoid a 2008 jail sentence for corruption, has a home.
"We heard that she went to Cambodia and then Singapore from where she flew to Dubai. She has arrived safely and is there now," said a senior member of the Puea Thai Party who declined to be named because he was not authorised to speak to the media.
Deputy national police chief General Srivara Rangsibrahmanakul said police had no record of Yingluck, 50, leaving the country and were following developments closely.
A Reuters reporter was stopped by security at the exclusive Emirates Hills community in Dubai, where Thaksin has a home.
A Thaksin spokesperson in Dubai did not respond to attempts by Reuters to contact Thaksin.
Police estimate that up to 3,000 supporters had gathered outside the court in Bangkok on Friday where Yingluck was due to hear a verdict in a negligence trial against her involving a rice buying policy of her administration.
But Yingluck did not show up at the appointed hour and the court quickly issued a statement saying she had cited an ear problem as the reason for her no-show.
The court rejected the excuse and moved the verdict reading to September 27. It later issued an arrest warrant for Yingluck.
Immigration police said they would arrest Yingluck on the spot if she is found.
Deputy Prime Minister Wissanu Krea-ngam said the government "should not comment" on Yingluck's case and her whereabouts.
"It's a matter for police to proceed with the arrest warrant," Wissanu told reporters, adding that her whereabouts "will be clear soon".
National police spokesman Dechnarong Suticharnbancha said on Saturday police were still investigating reports that Yingluck had either fled to Singapore or Dubai and said police had no new information on the matter.
Winthai Suvaree, a spokesman for the junta or National Council for Peace and Order, said there had been no security meeting to address Yingluck's disappearance.