Dari Jari Kak Peah

BANGKOK (Reuters) - Thousands of supporters of former Thai Prime Minister Thaksin Shinawatra thronged a Bangkok stadium on Saturday to hear his "phone-in" speech, which organisers hope will sway votes for a new premier next week.

The rally was meant to "stop the military intervention" in politics, rally organiser Jatuporn Prompan told Reuters, adding that the former ruling coalition is trying to cobble together a new alliance after some of its partners joined the opposition.

Thailand's parliament is expected to vote for a new prime minister on Monday, with the opposition Democrat Party the favourite to emerge at the head of a weak coalition government.

"The military and the Democrats are launching a disguise coup, claiming to have royal backing and coercing our friends to form a Democrat-led government," Jatuporn said.

Army spokesman Sunsern Kaewgumnerd denied the allegation, saying Army chief Anupong Paochinda has no formal power to do so. He was only "giving advice" to politicians who came to seek his opinion about a new government, Sunsern said.

The army has put 2,500 troops on standby to help 1,500 police officers keep peace during and after the rally if requested, Sunsern said.

Dozens of buses arrived at a downtown soccer stadium, unloading hundreds of red-shirted supporters with anti-military banners and slogans praising Thaksin.