The government has been urged to honour promises to protect the Post Office network ahead of the third reading of the Postal Services Bill later this month.

The Communication Workers Union (CWU) has warned that the Bill will cause more post offices to close. General secretary Billy Hayes said that the proposed privatisation of Royal Mail could take much-needed business away from the network. "Many of the proposals in the Postal Services Bill, including privatisation of Royal Mail and splitting the postal group apart, seriously threaten business arrangements for the Post Office."

Research by the CWU has revealed that over 1,000 post offices either closed or were put up for sale in 2010. Hayes said that the figure was higher than usual and added that many weren't officially registered as closures because the Post Office classifies them as 'temporary closures' as it hopes to find a buyer for them.

"Post offices have been closing at an alarming rate this year, but didn't register because they are misleadingly classed as temporary closures," he added.

However, property agent Christie & Co maintained that demand for post office premises remains high, with a 20% increase in properties sold in the year to November 2010.

Meanwhile, Scottish MPs are demanding that the government stands by pledges to ensure the Post Office network has sufficient work to guarantee against future large-scale closures. Members of a Scottish Affairs Committee who have been analysing the potential impact of the Postal Services Bill warned that despite a planned increase in funding, many post offices "remain vulnerable to closure".

The committee warned that the network in Scotland was in a "precarious position financially" with many rural post offices funded through a subsidy, leaving them vulnerable to closure.