A new e-mail vetting system at the House of Commons is stifling debate among MPs over serious parliamentary business such as the Sexual Offences Bill, it is claimed.

The system was introduced last month after MPs complained about getting inundated with pornographic and rude e-mails.

Any emails blocked by the filter can be released instantly with one phone call to our help desk House of Commons official

More than 900 e-mails were blocked in its first week, and the new system is now proving too restrictive and causing "chaos", according to one MP.

Lib Dem spokesman Paul Tyler says the system is now blocking parts of the Sexual Offences Bill being sent to parliamentary e-mail addresses.

It also blocked a Liberal Democrat consultation paper on Censorship.

Gagging debate

Mr Tyler said: "At a time when the government is trying to be transparent and Parliament is insisting on robust Freedom of Information legislation, this level of interference is totally over the top.

"This system may be designed to prevent MPs blushing from blue emails, but in practice it is blocking discussion of the new Sexual Offences Bill.

"Blocking filth is one thing, gagging political debate is another.

Censoring MPs discussions with their staff, colleagues and constituents is totally unacceptable Paul Tyler Lib Dem MP

"The system is less than a month old and is already in chaos. It was imposed on MPs with no warning and with no consultation.

"It must be suspended until all the wrinkles can be ironed out.

"Censoring MPs discussions with their staff, colleagues and constituents is totally unacceptable.

"Many constituents who have had perfectly reasonable emails blocked may not pursue the issue further.

"If MPs are so protected by the nanny state that they lose touch with the people, how can we possibly encourage more participation in politics?"

System defended

In the first week the new e-mail censorship system was introduced more than 900 e-mails sent to the Commons were ruled obscene.

But the House of Commons authorities insist measures were in place to ensure genuine e-mails were not lost.

A House of Commons official said: "Any e-mails blocked by the filter can be released instantly with one phone call to our help desk.

"We receive over half a million incoming e-mails a month - so far the filter has blocked about 900 a week, which is about 1 in 180, much less than 1%.

"The helpdesk has only received a handful of unblocking requests.

"On the whole the system seems to be working quite well - we're reviewing and fine tuning it as we go, so we always welcome feedback from MPs and their staff."