BANGKOK (AFP) - Thai Premier Yingluck Shinawatra called for calm Tuesday before a Constitutional Court ruling that could force the dissolution of her party and inflame the country's bitter divisions.

Ms Yingluck insisted she would not step down ahead of the court ruling, the latest challenge to her embattled government which has faced nearly three weeks of rallies sparked by an amnesty bill which could have allowed the return of self-exiled former premier Thaksin Shinawatra. "I don't want people to be emotional and clash with each other," the Thai leader, who is Mr Thaksin's sister, said Tuesday, urging pro-and anti-government groups to wait for the court's findings.

The court is set to rule Wednesday on whether efforts by Ms Yingluck's government to alter the constitution - drawn up under the military junta that deposed Thaksin - are legal. The proposed changes would make the senate, parliament's upper house, a fully elected body.

A verdict that the ruling party acted unconstitutionally in its push for the change could lead to its dissolution, with leading MPs facing five-year bans from politics.

This would risk fresh conflict in a nation that has been periodically rocked by bloody street rallies since huge protests helped topple Mr Thaksin from power in 2006.

"There is no reason for me to dissolve the house or step down. We can still ensure peace and order. There is a lack of continuity if the government keeps changing," said Ms Yingluck, who does not face a parliamentary ban because she is not listed as a party leader.

Judicial rulings have played an important role in politically turbulent Thailand.

Two pro-Thaksin premiers were forced from office in 2008 by them, making way for the opposition Democrat Party which is backed by the military and Bangkok's elite, to take power in a parliamentary vote.

Demonstrators linked to the opposition have remained on Bangkok's streets for several weeks in rallies against Thaksin and the ruling party, although their numbers have fallen since the amnesty was rejected by the senate on November 11.

The pro-Thaksin "Red Shirts" have also now begun to gather in the capital, vowing to oppose any decision that would remove another government linked to the ousted former premier.