The court rejected Ms Bhutto's appeal against her corruption conviction last month on the grounds that she must be in Pakistan before the appeal can be lodged.

Ms Bhutto has not returned to Pakistan since her conviction.

She is reported to be staying with her children in Dubai, where the family has a home.

Her appeal was lodged by lawyers in her absence, who were previously confident that the appeal would be accepted.

They now say they believe the ruling is wrong and they will now appeal against it.

'Strategy knocked off course'

Ms Bhutto now faces a crucial dilemma - whether to return to Pakistan and face arrest, or to remain abroad.

Government supporters and some members of Ms Bhutto's Pakistan Peoples' Party believe that if she stays abroad, then her credibility with the electorate will be severely undermined.

The BBC Correspondent in Islamabad, Owen Bennett-Jones, says Ms Bhutto's strategy now seems to have been knocked off course.

Aides close to the former prime minister had previously said that she was hoping to stay in Dubai until her appeal was lodged.

She then hoped that the Supreme Court would rule that her prison sentence should not be enforced until it had given a final verdict in her case.

Mr Zardari is already in prison

She and her husband, Asif Zadari, were convicted of corruption on 15 April.

They were sentenced to five years' jail and fined more than $8.5m dollars.

Ms Bhutto says the charges are politically motivated, and she is innocent.