Caretaker Interior Minister Kongsak Wantana said the gathering was aimed at honouring His Majesty the King on the 60th anniversary of his accession to the throne. Big celebrations of the special occasion had taken place all over the country last month.

Kongsak said the Dhammakaya gathering had been delayed as the Pathum Thani temple was not previously available.

"This event is not aimed at seeking political gains. Neither is it dominated by politics," the Interior minister said.

He said the gathering had no hidden agenda. Organised by the Interior Ministry and associations of local administrators, the event is called "Uniting All Religions for Rural Development and Honouring His Majesty's 60 Years on the Throne". It was planned more than two months ago, Kongsak said.

Deputy Premier and Justice Minister Chidchai Vanasatidya said the speculation had been generated by "somebody's imagination". He said he was concerned it would confuse the public. He said the gathering had no political implications.

The anti-government People's Alliance for Democracy says the government is holding the event as a subterfuge to mobilise its supporters.

However, the interior minister said the participants would go home immediately after the event was completed.

Kongsak is scheduled to preside over the event's opening at about 11am. At 6pm, caretaker Prime Minister Thaksin Shinawatra is to deliver a speech on how to utilise religious teachings in national development.