Thailand's constitutional court has ordered Yingluck Shinawatra to step down as prime minister after finding her guilty of abusing her power.

The court on Wednesday ruled that Yingluck had abused her authority by transferring a senior civil servant in 2011 to another position. It said the transfer was carried out with a "hidden agenda" to benefit her politically powerful family.

The court also ruled that nine members of her cabinet were complicit in the abuse.

"Her prime minister status has ended... Yingluck can no longer stay in her position acting as caretaker prime minister," the presiding judge, Charoon Intachan, said in a televised ruling. "Her prime minister status has ended... Yingluck can no longer stay in her position acting as caretaker prime minister," the presiding judge, Charoon Intachan, said in a televised ruling.

Niwatthamrong Boonsongphaisan, the the deputy prime minister, was named acting prime minister in place of Yingluck.

Thailand has had an acting government since Yingluck dissolved the lower house of parliament in December in a failed attempt to defuse six months of anti-government protests. A planned election was disrupted and then annulled.

A new election is planned for July 20.

A legal adviser for Yingluck's Pheu Thai party said the ruling was the latest attempt to destroy the country's democracy.

"The party has been supporting democracy in the country but there is a group of people and institutions that have been working systematically to destroy it. We call for the caretaker government and the election commission to keep working to hold the election on 20th July."

Protest fears

Yingluck's supporters accuse the courts of toppling her through unfair use of the legal system. Threy have vowed to hold a major rally on Saturday, which many fear could spark violence.

On Tuesday Jatuporn Prompan, the chairman of Yingluck's "Red Shirt" supporters said: "I expect the verdict will not be good for the government.... I heard they want to sack the entire cabinet.".

The constitutional court oversees cases of violations of Thailand's charter, which was rewritten after the removal of Thaksin Shinawatra as prime minister in an army coup in 2006. Thaksin lives overseas to avoid jail for corruption convictions.

Yingluck, Thaksin's sister, has also been charged by anti-corruption officials with neglect of duty in connection with a costly rice subsidy scheme that critics say fomented rampant corruption.

An unfavourable ruling by that body could also lead to her impeachment and a five-year ban from politics.

Thailand's courts, like its military, are seen as bastions of anti-Thaksin conservatism, and have a record of hostile rulings toward Thaksin's political machine, which is fueled by billions of dollars that he made as a telecommunications tycoon.

Analysts said on Wednesday's ruling further sullied the courts' reputation.

"The credibility of the justice system has vaporized," said Thongchain Winichakul, a professor of Southeast Asian history at the University of Wisconsin. ``The royalist conservatives may celebrate this judicial coup. But the world will mourn over the death of another democracy."