BANGKOK--A Thai pro-government group said it hopes to gather up to 10,000 people at a rally Sunday to show support for the premier, raising fears of clashes with rivals who have occupied the city's airports.

The group, known informally as the "Red Shirts" but officially called the United Front for Democracy Against Dictatorship (UDD), plans to gather Sunday at about 4:00 pm (0900 GMT) in Bangkok's government district.

This would put them just kilometers away from some supporters of the anti-government People's Alliance for Democracy (PAD), who have occupied the nearby prime minister's cabinet offices since late August.

"So far we have plans to talk to our supporters and show support," said Somyos Preuksakasemsuk, a leader of the pro-government group, adding that they hoped to gather up to 10,000 people.

"The leaders will later decide how long the gathering will last for."

The UDD had originally planned to rally at Bangkok's Sanam Luang plaza, a large grassy area, but preparations for a royal event forced the demonstration to move to a square in front of the Bangkok Metropolitan Administration building.

The PAD, whose supporters wear yellow shirts and headbands in what they say is a symbol of their desire to protect Thailand's revered monarchy, is locked in a stand-off with police at Bangkok's two main airports.

Clashes between the pro- and anti-government groups have broken out sporadically across Thailand recently and people fear a large-scale confrontation between the so-called Red Shirts and the Yellow Shirts.

The pro-government side are supporters of ousted and exiled prime minister Thaksin Shinawatra -- the object of the wrath of the PAD, which claims the current government is doing his bidding.

In early November, Thaksin gave a telephone address to a gathering of about 100,000 supporters on the outskirts of Bangkok, in which he said "the power of people" could bring him back from exile.