The founder of the Dignitas institute in Switzerland, Ludwig Minelli

Britons planning to travel to Switzerland to take advantage of its liberal assisted suicide laws are facing a crackdown on the practice by the Swiss government.

More than 100 Britons with terminal or incurable illnesses have used the Swiss clinic Dignitas to kill themselves.

But now Swiss justice minister Eveline Widmer-Schlumpf has unveiled proposals that will force assisted suicide centres to follow strict guidelines or risk prosecution - or even ban them completely.

"As a country, we aren't interested in attracting suicide tourism," she said.

The new rules would require groups to exhaustively document their contact with patients. Patients also would have to obtain two medical opinions proving their illness is incurable and likely fatal within months, and that they are capable of making an informed decision to end their lives.

Ms Widmer-Schlumpf said: "It won't be possible in future for someone to cross the border and commit suicide a few days later with the help of an organisation because a minimum amount of time will be required."

A second proposal also being considered would ban organised assisted suicide completely. The justice minister said this would be the easier option, but would most likely force the practice underground.

Dignitas founder, Ludwig Minelli, branded her proposals "outdated and "patronising".

According to official statistics, some 1,360 people committed suicide in Switzerland in 2007. Of the 400 who turned to assisted suicide groups for help, 132 came from abroad.

The government has opened the proposal for public comment until March 1, after which it will send a draft law to parliament.