A further 4,000 post offices could be closed on top of the 2,500 scheduled to shut, a committee of MPs is set to warn this week.

Royal Mail is now expected to fall far below a government pledge that the national network of post offices should be kept to at least 11,500.

The Commons business and enterprise select committee is expected to express anger about the company’s refusal to guarantee it will end the closure programme.

MPs on the committee, chaired by the Conservative Peter Luff, are so concerned that they are likely to call on Postcomm, the regulator, to investigate Post Office Ltd, the Royal Mail subsidiary that runs the network.

The company has shut 4,600 outlets in recent years, bringing the total to 14,000, and has announced 2,500 more closures despite widespread anger.

When asked by one MP about the government’s guarantee of 11,500 post offices Royal Mail replied: “It is not possible or desirable to set a minimum number of fixed outlets.”

The committee wants Royal Mail to try harder to keep post offices open, particularly in villages where there are few other local facilities, and in poor urban areas.

Royal Mail has indicated, however, that the criteria it is required to meet are present in only 7,500 outlets.

“The government wants a network of 11,500 but the Post Office has said it is unnecessary to set targets,” said a source close to the committee. “They are not committed to maintaining the network at this level – 4,000 more offices could close and still meet the government’s criteria.”

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