Claims have been raised in Victoria's Parliament that an Australian executive jailed in Dubai earlier this month was the victim of witness tampering by another Australian development company.

Earlier this month Matthew Joyce was found guilty of fraud and jailed for 10 years over a property deal gone sour in Dubai.

The deal involved the sale of waterfront land in the UAE by the Dubai-based firm Mr Joyce worked for to Gold Coast-based developer Sunland.

Victoria's shadow treasurer, Tim Pallas, has used parliamentary privilege to accuse Sunland of tampering with a witness in the Dubai case.

Sunland has since issued a statement denying Mr Pallas's claims.

Mr Pallas says Sunland signed a deed with Gold Coast lawyer Anthony Brearley in which the property group promised not to sue him if he swore an affidavit on agreed lines regarding claims of bribery involving Mr Joyce.

In tabling the deed in Victorian Parliament this morning, Mr Pallas said "Mr Joyce was falsely accused of criminal behaviour, extraordinarily by another Australian company, which was under investigation for bribery."

"I regret to inform the house that shocking new evidence has arisen of witness tampering that seems to have been specifically designed to damage the interests of Mr Joyce," he said.

"I have here a deed that unequivocally demonstrates the lengths to which Mr Joyce's accusers have gone to falsify the evidence against him, both in Dubai and in Australia."

The deed between Sunland and Mr Brearley states that Mr Brearley worked as legal counsel under Mr Joyce at Dubai Waterfront.

It says that during a face-to-face conversation in either late 2008 or early 2009, Mr Joyce told Mr Brearley that a separate investment firm, Prudentia, had paid "quite a few million Dirhams" into his back account.

The deed says Prudentia had been interested in purchasing the waterfront land in Dubai.

It says "Mr Brearley specifically must not disclose this deed or the fact of this deed to any Dubai authorities."

Details emerge of Joyce's time in solitary confinement

When tabling the deed in Parliament, Mr Pallas detailed the shocking conditions of Mr Joyce's arrest in Dubai following a meeting with police in January 2009.

"He was not allowed to leave this meeting and was incarcerated in solitary confinement at Dubai state security for seven weeks," he said.

"He did not see light of day once in this period. The room was two metres by three metres, with no windows or bathroom and a grass mat in the corner for a bed.

"When he was finally allowed to see his wife a month later, he was white, clammy and weeping, with sores from the cold floor and malnutrition."

Mr Pallas says bringing Mr Joyce home is a matter of great importance to all those who know him.

"I believe the information provided to this place is critical to ensuring that justice prevails and that Mr Joyce comes home," he said.

Sunland says witness tampering claims 'fanciful'

Meanwhile, Sunland has expressed disappointment at the actions of Mr Pallas and says the allegations it tampered with a witness are incorrect.

"The comments on the deed given by the shadow treasurer do not accurately and fully reflect its terms," a statement from the company said.

"Anthony Brearley and Sunland entered into the deed, pursuant to which Mr Brearley agreed to provide truthful evidence if required in a civil proceeding in Australia."

Sunland says the allegation it tampered with a witness is "fanciful".

Sunland had also brought civil action against Mr Joyce over the same matter in the Victorian Supreme Court but that was dismissed in June 2012.

The court strongly criticised the evidence of Sunland's key witnesses and the judge ordered Sunland to withdraw its claim against Mr Joyce in Dubai.

The court in Dubai has also fined Mr Joyce $25 million. He says he will appeal the verdict.

His former business partner, Marcus Lee, was acquitted.