Tony Chan Chun-chuen, the businessman accused of forging a will he claimed to be from late Chinachem chairwoman Nina Wang Kung Yu-sum, is seeking to halt his trial for good, a court heard yesterday. Chan says the document has been materially altered by chemicals used in forensic tests by the authorities, making it impossible for his experts to conduct their own tests. The authorities ran tests on the document while investigating Chan. The defence team intended to apply for a permanent stay of criminal proceedings over the forgery charges, Alan Hoo SC, for Chan, told Acting Principal Magistrate David Dufton in Eastern Court. Chan, 52, is charged with one count each of forgery and of using a false instrument in relation to a purported will of Wang, who died of cancer in April 2007, aged 69. Her estate is estimated at HK$50 billion. Chan's lawyers are due to exchange documents on the stay application with prosecutors in coming weeks. Hoo said the will had undergone tests in which chemical solvents were used. The colour of the document had been changed. 'After an inspection by our witnesses, they informed us that the documents had gone through a very material alteration,' he said. The lawyer said Chan's experts wanted to look for DNA from Wang and from people who were named as attesting witnesses on the document. They had also been interested in a stamp on the document and the typescript used. It was written using an old-fashioned typewriter, he said. The criminal case is due for a preliminary hearing on May 14. Chan's legal team wants the stay application to be heard at the beginning of those proceedings and expects it to take up the first three days of the hearing. The magistrate said he would be handling that hearing. Director of public prosecutions Kevin Zervos said there was a question as to whether the application should be made at the preliminary hearing, and that the issue depended on the nature of the stay application. He said he was informed of the intended application yesterday. Prosecutors were trying to arrange for counsel from overseas to represent them, Zervos said. Chan was accompanied at the hearing yesterday by his wife, Tam Miu-ching. The defendant was released on bail. His younger brother, Ricky Chan Chun-kwok, has previously provided a surety of HK$20 million as part of his bail conditions. Tony Chan is also on bail of HK$20 million cash. He must report to a police station twice a week and cannot leave Hong Kong.