But Mr Howard has denied he released the report to influence debate on the issue, as Liberal backbenchers including Senator Kay Patterson and MP Mal Washer questioned the need for a second report, its independence and the timing of its release.
The government received the report in June, the same month cabinet voted to ignore the Lockhart findings, but released it only yesterday.
"Releasing the report was not designed to influence the debate," Mr Howard said. "I knew I had to release it because there was a freedom of information request in, and I thought the most sensible thing to do was to put it out on the table straight away."
Therapeutic cloning is a laboratory procedure that involves taking the nucleus of a human cell and injecting it into a modified egg to create an embryo from which embryonic stem cells can be extracted.
The new report found the Lockhart review did not provide enough evidence on scientific developments since 2002 that would justify changes to the legislation. Parliament voted in 2002 to maintain the ban.
Mr Howard has promised his MPs a conscience vote should any legislation, which could allow scientists to create embryos to produce stem cells if the ban is lifted, comes to parliament.
Cash for comment claim
Liberal backbencher Mal Washer, a supporter of therapeutic cloning, said the new report by Canberra-based mpconsulting smacked of cash-for-comment.
Mr Howard said while Dr Washer was entitled to his views, there would have been accusations of a cover-up if the government had not released the findings of the new report, while Health Minister Tony Abbott denied the government bought an opinion in an attempt to skew the debate on therapeutic cloning.
But Mr Abbott said the government was simply seeking the latest advice on the issue.
"My understanding is that this is a firm which has been used by the government from time to time to seek the latest advice on these sorts of issues," he told the Nine Network.
The report, commissioned by the Department of Prime Minister and Cabinet, was already the subject of a freedom of information request and the government decided to make it public, Mr Abbott said.
"(The Department of Prime Minister and Cabinet), quite understandably, after receiving the Lockhart report wanted to know what objective factors the opinions in the report had been based on," he said.
Mr Abbott said opinions about the future of stem cell research were divided in every political party and added the debate would ultimately turn on "ethical considerations, not scientific considerations".
Mr Abbott, a staunch opponent of expanding stem cell research, this month lashed out at scientists, accusing them of "peddling" hopes of cures without convincing evidence that therapeutic cloning would deliver results.
Today he confirmed that Australia's Chief Scientist Dr Jim Peacock, who last month warned Mr Howard's cautious approach to stem cell research could prevent a scientific breakthrough, would be invited to address MPs next week.
Report queried
Liberal Senator Guy Barnett today said he thought the report had the potential to persuade MPs the laws did not need to be changed.
The opposition Labor party joined with Liberal backbenchers Senator Kay Patterson and Mal Washer to question the need for a second report.
"The Howard government is pretty good at getting the advice it wants to hear," opposition health spokeswoman Julia Gillard said.
"The question for John Howard and Tony Abbott is why is this review better than the Lockhart Review? The Lockhart Review was a review the Parliament wanted, a review that was conducted by experts, a review that included proper public consultation."
Joanna Knott, convenor of the Coalition for the Advancement of Medical Research Australia, said the Lockhart review was a "masterpiece of thoroughness, fairness, and clarity of argument" while the new report failed to consider its more than 1,200 submissions.
Cabinet rejected the Lockhart review's recommendation in June, but Mr Howard last month bowed to backbench pressure and promised his MPs a conscience vote should any legislation come to parliament.
Australian Democrat Senator Natasha Stott Despoja and Ms Patterson, a former health minister are preparing private members' bills intended to end the ban on therapeutic cloning.
Senator Patterson hopes to have the private member's bill debated in parliament by the end of the year, her office said today.
Company destroyed embryos
Meanwhile, a United States biotechnology company that last week announced a new technique for creating stem cells without destroying embryos, has admitted it destroyed all 16 embryos used in the experiment.
Advanced Cell Technology said at the time the new embryo-sparing approach could overcome ethical objections to stem cell research.
But today it admitted it had just speculated that the embryos would have survived the procedure, based on other research showing single cells can be removed from embryos without killing them.