BEIJING, Aug 1 (Reuters) - The ousted Communist Party chief of Shanghai, China's financial heart, faces accusations of graft involving US$595 million and of making one of his mistresses have three abortions, a Hong Kong newspaper said on Wednesday.

The former party secretary of Shanghai, Chen Liangyu, was expelled from the ruling party last week and handed to judicial investigators, moving forward China's biggest corruption case in years. But the public charges against Chen have remained sketchy.

A Hong Kong newspaper under Beijing control, Wei Wei Po, has now shed some light on accusations that could land Chen a tough punishment as the party leadership seeks to show its willingness to tackle corruption among senior officials.

The paper said Chen diverted 3.5 billion yuan ($463 million) from city pension funds to lend to a crony's business, citing unnamed sources familiar with the case. It did not say what, if anything, Chen received in return.

Chen released another billion yuan to another company that in return gave his son, Chen Weili, well-paid top positions that needed no work. The total amounts to $595 million.

Starting when Chen was still a Shanghai district official in the 1980s, he and his family took bribes of at least 2.6 million yuan ($344,000), the paper reported, noting that the sum was not as large as many observers had speculated.

From 1991, Chen kept two long-time mistresses and "for a long time maintained improper sexual relations" and had liaisons with many other women, the paper said. He forced one of the mistresses to have the abortions, it said.

As the top official in booming Shanghai, where land prices have rocketed in recent years, Chen also helped his brother acquire land at windfall prices, it said.

The likely trial of Chen comes as President Hu Jintao prepares for a party congress in coming months that is set to give him five more years as national party chief and consolidate his grip on officials who have not always embraced his authority.

Felled last September, Chen was the first member of the party's Politburo -- an elite council -- to be purged for corruption since 1995. A dozen other officials and business people have since been implicated by a spreading inquiry.

Another Hong Kong-based newspaper controlled by Beijing, the Ta Kung Pao, reported last week that Chen's son was recently detained in Malaysia.