A committee of MPs last night criticised as ''unacceptable'' the range of areas which the Government thinks should be excluded from proposed freedom of information law.

Although generally welcoming the Government's proposals for a Freedom of Information Act, the Public Administration Committee's report, warned that in some cases the plans could actually reduce the extent of public access to information.

''We are disappointed that the exclusion of some - albeit only a few - areas from the risk of disclosure under the Act will, in some points, be inferior to the current Code of Practice on Access to Government Information,'' it said.

''We consider this to be unacceptable.

''We have been impressed by the breadth of the White Paper's commitment to freedom of information, but this has made the Government's decision to exclude certain bodies and classes of information all the more regrettable.''

Chancellor of the Duchy of Lancaster Dr David Clark published the Government's proposals for legislation in the White Paper Your Right to Know, in December.

The committee singled out for criticism the proposed exclusion of information relating to law enforcement, covering not only the police and prosecuting authorities but other bodies responsible for law enforcement, such as the Social Security Department and the Immigration Service.

It recommended that law enforcement information should not be totally excluded from the Act. Instead, it should be disclosable, but with the safeguard that it would be subject to a test of whether disclosure would cause harm, rather than ''substantial harm'', thus bringing it into line with the existing code of practice.

The MPs also recommended that the Security and Intelligence Services (SIS) should not be excluded from the proposed Act.

Although almost all information relating to SIS would in practice need to be withheld, they said, the SIS should be included in the Act as a point of ''important principle''.

This was because exclusion prevented any external view being taken on whether there might be cases in which the public interest over-rode the need for secrecy.

The report also criticised the White Paper's suggestion that the Act should not permit disclosure of information that would be banned under the Official Secrets Act.

''If the Official Secrets Act is allowed to determine the way in which decisions are made under freedom of information, it could easily become the means by which public authorities are able to cover up their mistakes,'' it added.

The MPs also warned: ''We have serious doubts that the regime proposed strikes the right balance between privacy and openness, or indeed whether it will be workable.''

Overall, however, the MPs welcomed the proposed Freedom of Information Act as ''a major plank in the Government's proposals for constitutional reform, and a radical advance in open and accountable government.''