The Switzerland-based organisation that helps British people commit suicide has opened up a second office to meet demand for its services. In addition, it has emerged that there are now at least six separate organisations in the country helping people to end their lives.

News that Dignitas has opened another clinic has been seized upon by pro-euthanasia groups in Britain, which warn that an increasing number of people will go abroad to end their lives unless UK law is changed.

'These developments show that this problem is here to stay, and can only get worse. There is a crying need for change. We have to find our own answer in Britain,' said Deborah Annetts, chief executive of the Voluntary Euthanasia Society (VES).

Details about the clinics emerged after a committee of British politicians examining proposals to change UK laws banning euthanasia paid a secret visit to Switzerland earlier this year. The committee was seeking evidence in relation to Lord Joffe's private member's bill, which seeks to change the law so that terminally ill, mentally competent people can be given help to end their lives. The committee's findings will be published this month.

Dr Andreas Brunner, attorney-general for the canton of Zürich, told the committee that Dignitas, which previously was thought to operate solely out of Zürich, was now renting a house in the neighbouring canton of Aargau, which it was using to help people, mainly foreigners, commit suicide. Of the 20 or so people the second clinic has assisted so far, seven were from Britain, Brunner said.

'In the late 1980s there was the first suicide organisation in Switzerland,' Brunner said. 'Now we have five or six organisations and some splinter organisations also.'

It is estimated that, since 2000, more than 30 Britons have ended their lives in Switzerland with help from Dignitas. But the overall number of Britons who have taken their lives in the country could be significantly higher now it has emerged there are several clinics helping foreigners die.

The committee heard there has been a sharp rise in the number of foreigners visiting Switzerland to commit suicide, a phenomenon that has been labelled 'death tourism'. Dignitas helped 93 people end their lives in 2003 - a record year - of which 'only two were from Switzerland', Brunner said. As of 3 February this year, there have been 362 deaths in Dignitas's clinics.

Brunner warned that the phenomenon was becoming difficult to monitor as the number of death tourists increased and the informal network of doctors prescribing lethal drugs rose accordingly. 'They leave before the police come,' Brunner said of the doctors. 'They give the people barbiturate and then they go ... Certain doctors give quite quickly the prescription and then they do not care about people.'

The VES, which is backing Lord Joffe's Assisted Dying for the Terminally Ill Bill, said there was an urgent need for a change in the law: 'In Switzerland, assisted dying is virtually unregulated. The Joffe bill would bring safeguards, choice and transparency for people who are suffering unbearably.'

But opponents said any change in the law would put doctors under pressure. 'We think doctors are here to save lives and not end them,' said Mark Bhagwandin, public relations officer with the anti-euthanasia group Life. 'The bill challenges doctors to work against the Hippocratic oath.'

And he warned it would open the door to euthanasia on demand: 'How do we police it? How do we know people are not being pressured into making the wrong decision to end their lives?'