"Is that all you can think of? How shameful. How can you say that there are two prime ministers?"
Samak was appointed to lead a coalition government earlier this year after his People's Power Party (PPP), widely considered a proxy for Thaksin's disbanded Thai Rak Thai party, won national elections.
Thaksin is officially barred from politics for the next four years.
"I am the real prime minister. I am no one's nominee"
Nonetheless many analysts expect that with his return to Thailand PPP cabinet members will now defer to the former leader, undermining Samak's authority.
On Thursday, hours after Thaksin returned to a rapturous welcome from supporters, Thailand's finance minister told reporters that the government would consult the former prime minister for economic advice.
"We can't appoint him to any official position, but we'll ask him for advice on the economy," Surapong Suebwonglee said.
Thaksin himself spent Friday whipping up a public relations blitz, featuring football clinics from children with players from his Manchester City club and paying a visit to Thailand's most senior Buddhist monk.
|Thaksin has denied he has any plans |
to return to politics [AFP]
The former prime minister has said repeatedly he has no plans to return to politics, and has come home to clear his name of corruption allegations.
On Thursday, shortly after his return, he was formally charged by Thailand's supreme court and released on bail.
However, supporters and critics alike have cast doubts on Thaksin's renunciation of politics, saying they expect him to become a key power behind the scenes.
"He's in the back seat but he is still driving the car," Jon Ungpakorn, a former senator turned activist, told the Associated Press.
His comments were echoed in the Thai language Thai Post newspaper which said in an editorial on Friday that Thaksin's behaviour "totally contradicts what he says".
"His behaviour makes it clear that he came back to reclaim his power - to show that he is the real leader," the paper said.
Critics have said that a renewed political role for Thaksin could reignite the deep tensions that provoked mass demonstrations ahead of the 2006 coup.