Liberal Democrat science spokesman, Dr Evan Harris, who has tabled a private member's Bill to allow UK labs to work in the field, has accused the government of political cowardice.
A panel of experts convened to examine the merits of the technology should have had their findings made public six months ago.
But their report, although now in the hands of the government, has yet to be acted upon.
The Department of Health will only say that ministers are taking their time to consider "complex and difficult" issues.
Therapeutic cloning is distinct from the type of cloning that would result in exact copies of individual people.
Paper speculation
This limited form of cloning involves taking genetic material from a single, adult cell and using it to make an embryo. This is then "harvested" for powerful cells that could form the basis of revolutionary medical treatments.
The technology is fiercely opposed by some religious and anti-abortion groups who object to the use of human embryos, whatever the benefits, in scientific research.
But pressure is now mounting on the UK Government to decide its position on the matter. Some scientists are already threatening to leave for the US or other countries to carry out research if a decision is not made soon.
The expert panel, chaired by England's chief medical officer, Professor Liam Donaldson, handed its advisory report on therapeutic cloning to the government in May. The report itself was three months late.
A Department of Health spokesman said: "The government will be publishing the report and its response in two weeks' time. Obviously that is when we will make the government's view known."
On Sunday, the government dismissed reports it had already decided to give the green light to the research. Science minister, Lord Sainsbury, described the reports in the Observer newspaper as "pure speculation".
Ethical concerns
Ruth Deech, chairman of the Human Fertilisation and Embryology Authority, said approval of therapeutic cloning "must be on the minds" of the government.
She told BBC Radio that nobody wanted the cloning of babies, but there was a growing consensus that good could come out of the limited cloning methods some scientists now propose.
"The research would be looking for ways to grow new cells and tissues to help people with Parkinson's, with Huntington's, with Alzheimer's, with cancer and with burns."
She added: "It will be gradual and every step will be checked by us. We give licences and we can take them away."
But Tom Horwood, spokesman for the Catholic Church, said: "We are fundamentally opposed to any such development.
"A human embryo is a human life. It is creating a human life for the purposes of cloning."