DHAKA (AFP) - Bangladesh's main opposition leader, ex-prime minister Khaleda Zia, has been accused of abuse of power and graft in a new case filed by the country's main anti-corruption body, police said Monday. The charges relate to donations of up to 78 million taka ($1.05 million) made to a charity named after her late husband, independence hero Zia Rahman, when Zia was prime minister, police inspector Mahfuzul Haq said. "She has been named as the main accused in the case" filed by the country's Anti-Corruption Commission, Haq said, adding that three other people including Zia's political secretary had also been charged. Zia used her position as prime minister to force people to donate to the charity, said the commission's lawyer, Syed Anisul Haq. "The money was then spent in a questionable way," he told AFP. The commission is a nominally independent body but the opposition claims it is not politically neutral. This is the second graft case against Zia filed under the present government, which is led by her bitter rival, Prime Minister Sheikh Hasina. Zia, who leads the Bangladesh Nationalist Party, was prime minister twice. Her party was crushed in the last parliamentary elections by Hasina's Awami League. Both Hasina and Zia were detained for a year until the middle of 2008 as part of an anti-corruption crackdown launched by the then army-backed caretaker government. The charges against Hasina have all been thrown out since she came to power in December 2008 elections. In 2009, Zia and and her eldest son Tareque Rahman were accused of "gobbling up" 21 million taka donated to an orphanage trust, also named after Zia's husband. The orphanage was never built and the money was siphoned off through Zia and Rahman's aides, it was alleged at the time. The case is still outstanding. On Monday, in a separate case, a court in the Bangladeshi capital Dhaka issued an arrest warrant against Tareque Rahman, Zia's heir apparent, accusing him of laundering over 204 million taka ($2.73 million) in Singapore between 2003 and 2007. In June, Zia's youngest son Arafat Rahman Koko was convicted and sentenced to six years in jail in absentia for laundering more than 2.7 million dollars through bank accounts in Singapore. Tareque Rahman lives in exile in Britain and Koko is belived to be living in Malaysia. In recent months the BNP has enforced a series of crippling nationwide strikes protesting against electoral changes by the government. Analysts warn the new cases could trigger further protests by the BNP.