"The incontrovertible evidence proves that the previous government committed a big fraud on the people of Pakistan," the official APP news agency said.

It said the documents were given to the Pakistani ambassador in Warsaw and then relayed to the ministry of foreign affairs in Islamabad, which passed them on to the investigating authorities.

The report was published while Bhutto was in Dubai pending an appeal to the Supreme Court against five-year jail terms and an $8.6 million dollar fine handed down to the couple for corruption on April 15. No date for the appeal has been set.

Zardari, a former minister in his wife's cabinet, is already in jail on other corruption charges but is periodically released to attend sessions of the senate, of which he is a member.

APP said Zardari and Bhutto,twice elected Prime Minister and twice fired for alleged corruption, "skimmed" Rs 103 mn rupees ($ 2.0 mn) from a scheme to make available inexpensive Polish tractors in a bid to boost farming output.

The news agency cited sources at the country's Ehtesab or accountability bureau, which is leading investigations into what the government calls massive diversion of funds by the couple.

Bhutto says Prime Minister Nawaz Sharif's government is pursuing her to choke the voice of her opposition Pakistan People's Party (PPP) and end her political career. The government denies the charge.

"The documentary evidence received from Poland confirms the scheme of kickbacks laid out by Asif Zardari and Benazir Bhutto in the name of (the) launching of Awami tractor scheme," APP said.

It said the scheme was initiated to pocket Rs 103 mn rupees in kickbacks, not to benefit farmers.

APP said the case was pending before an Ehtesab court since last year when it received nearly 800 pages of documents from Geneva afterasking the Swiss authorities to cooperate.

Switzerland also provided documents that helped convict Bhutto and Zardari of receiving huge kickbacks in the award of a government contract to the Swiss firm SGS to stop customs fraud.

The report followed publication in the Pakistani media of official pre-emptive denials of allegations of corruption by Sharif which are expected to be aired in a British Broadcasting Corporation documentary next month.

A series of official statements have said that "evidence" to be aired by the BBC was provided by Bhutto associates and discredited. The official media have denied charges of tax evasion and loan fraud by the prime minister.