Britain's fertility regulator carried out unannounced inspections today at two IVF clinics run by a doctor at the centre of a Panorama investigation to be broadcast tonight.

The Human Fertilisation and Embryology Authority (HFEA) said it obtained a court warrant this morning to inspect the two London clinics run by Mohamed Taranissi.

Two HFEA inspection teams, with police officers in attendance, visited the Assisted Reproduction and Gynaecology Centre and Reproductive Genetics Institute in London to carry out the inspections.

The warrant came after it was claimed an undercover reporter was offered "unnecessary and unproven" treatment by one of the clinics, the ARGC.

Staff from the medical centre were secretly filmed during an investigation by the BBC programme which alleged one of the therapies offered was a potential health risk to an unborn baby.

Mr Taranissi is also accused of continuing to operate another fertility centre which no longer has a treatment licence.

The clini owner, who has produced 2,300 babies during the past seven years and is reportedly worth more than £30m, strongly denies the allegations.

Angela McNab, chief executive of the HFEA, said in a statement: "For some time the HFEA has been taking regulatory action against the clinics run by Mr Taranissi. This is a matter we have been treating very seriously."

She insisted that inspections were "entirely separate" from the Panorama investigation.

Ms McNab said: "We have received information from whistleblowers who appear to have been working in the centre. We are also aware of the separate allegations made in the BBC Panorama programme which will need investigation."

She said: "We have faced unique difficulties with the clinics run by Mohamed Taranissi. While we have tried to work with his clinics to get the information we require to do our job we have been challenged by this clinic and its lawyers at almost every step of the way. This has greatly lengthened the time it has taken to tackle these issues."

The Panorama investigation alleges a 26-year-old undercover journalist was offered IVF treatment costing thousands of pounds at the ARGC despite neither her, nor her partner, having any history of fertility problems.

Following a blood test on the reporter, a clinician said the results showed her "antibodies were found to be high" and suggested she enrol for full IVF treatment involving a transfusion of antibodies and a course of steroids. Fertility expert Professor Lord Winston described the treatment as having "no basis, no justification".

The undercover reporter was also told she needed blood tests involving 18 separate samples at a cost of £780. But another expert, Professor Lesley Regan from St Mary's hospital, London, told the programme the tests were worthless.

Panorama also claimed Mr Taranissi's second clinic, the Reproductive Genetics Institute (RGI), had continued giving treatments to patients even after its licence was not renewed at the end of 2005, due to a lack of required data.

A league table published last week by the HFEA showing the performance of the UK's fertility clinics ranked both Mr Taranissi's centres among the worst in the country.

The HFEA confirmed that Mr Taranissi's clinic, the RGI, had been licensed to treat IVF patients until December 31 2005, but did not have a treatment licence after that date.

In a statement given to the BBC programme, Mr Taranissi said: "My clinics have always been well run, safe and reputable - and the practices I favour have led the independent HFEA regulator to conclude that ARGC, my main clinic, enjoys the highest success rates in its field since 1995.

"The Panorama programme is wrong on many key facts.

"The programme makers question the efficacy of immune testing in IVF, yet I am open about the fact that it is indeed one reason for my success rates.

"Panorama says that my second clinic, RGI, operated for a while without a licence. As explained to them, this is a matter of legal dispute.

"The clinic in question was offered a three-year licence. On the form accepting this, I said I wish to make representations.

"The HFEA regulator seemed to interpret this two months later as me declining the licence, and the matter has been with the lawyers ever since."

Panorama will be screened tonight on BBC1 at 8.30pm.

The HFEA has set up a patient helpline on 020 7291 8222, with lines open between 8.30am and 5pm.

People can also email helplinehfea.gov.uk.