A TELECOMMUNICATIONS firm with a strong base in the North-East may have become the first in the UK to put a mandatory block on Internet porn.

Last night, Home Secretary Jack Straw "broadly welcomed'' ntl's initiative in introducing a filter system -denying access to hardcore material to all but streetwise Internet users.

Teesside firm ntl has introduced zero tolerance policing of the Internet via its ntlworld service with a filter - set by ntl - from nought to five, with nought even excluding references, on educational sites.

The ntlworld search results are set at one, which means that a limited number of educational sites are included. Five would be totally unfiltered.

The changes were introduced by the firm as Mr Straw prepared to meet Internet service providers and search engine firms. He was due to warn them to introduce self regulation or face possible legislative powers.

A Home Office spokesman said: "I think it would be fair to say that the Home Secretary, as a representative of the Home Office, but also as a parent, would broadly welcome anything that gives more protection to children and to, indeed, more vulnerable members of society.''

AOL, one of the country's biggest Internet providers, has a certificated Internet access system with material graded to a child's age.

Telewest, the main internet provider for Tyne and Wear and Northumberland, recommends that parents use Cyber Patrol software to block out sites.

Middlesbrough firm Onyx Internet uses Websense software, used by schools, to prevent access to hardcore material.

Meanwhile, ntl says that while the customer feedback is generally enthusiastic, not everyone is happy and the filter could be increased to two on the scale.

A spokeswoman said: "It is still possible that ntlworld users who do not want to be restricted by the filter can - if they wish - leave our site and use an alternative engine provider.

"However, our aim is to provide the best search possible and the best content possible, to ensure users want to stay within our area.''

A spokesman for the anti- censorship lobby www.netfreedom.org, said: "Not all who use the Internet are children and people should be able to make up their own minds as to what they should read, watch and listen to.'