Dhaka, Aug 20 (IANS) The Bangladesh government has refused to extend the parole of opposition leader Khaleda Zia's son Arafat Rahman Koko, living in Bangkok for over two years, and asked him to surrender before a court by Aug 31.

Koko, a businessman, has been accused of illegal business deals and financial transactions when his mother was the country's prime minister 2001-06.

The government's move, in the form of a home ministry order issued Thursday, could sharpen the differences between Zia and her political rival, Prime Minister Sheikh Hasina, political analysts said Friday.

The government acted on a day Zia told a rally that the Hasina government should "admit failures, step down and work in cooperation with the opposition and all concerned", The Daily Star reported.

Koko, as also his elder politician-brother Tarique Rahman, left Bangladesh citing medical grounds in December 2008 as part of an understanding reached with the then government in the run up to the parliamentary poll.

While Zia lost the poll, Hasina won a landslide majority.

Tarique, since anointed senior vice president of the Bangladesh Nationalist Party (BNP) that his mother leads, continues to live in London.

Several cases are pending against Zia and her two sons, all of whom were detained during 2007-08.

The government refused to extend Koko's parole that expired last week, saying he was not reporting on his health condition to the Bangladesh embassy in Thailand.

"We appealed for the extension of his parole on health ground. His condition is still very critical. Koko, now under treatment, maintains regular contacts with the Bangladesh mission in Bangkok," his lawyer A.M. Mahabubuddin told New Age newspaper.