The decision by the Foreign Office not to remove the pension rights from Coghlan was attacked as "weak" by Harry Cohen, the Labour MP for Leyton, who also demanded the tightening up of vetting procedures on diplomats to stop other paedophiles being employed by the Government.
Jeremy Hanley, a Foreign Office minister, said in a letter to Mr Cohen that the Foreign Office had given "careful consideration" to the question of stripping the diplomat of his pension.
"We have concluded that, under the rules of the Principal Civil Service Pension Scheme, his activities do not constitute grounds for depriving him of his pension," Mr Hanley said. The pension will be based on Coghlan's final salary and years of service at the time of his dismissal and will remain frozen until he reaches the age of 60.
Coghlan, 54, was sacked after being sentenced for importing from Japan to Britain 109 pornographic videos involving children, en route to another posting, using the diplomatic bag.
Mr Hanley said that in the light of the Coghlan affair, the rules for transporting personal effects are to be changed to include pornography among the list of illustrative items which are prohibited from being carried in the diplomatic bag. All diplomats are warned that prohibited items cannot be taken by diplomatic bag, which can include containers covered by diplomatic privilege but previously were not specifically told to exclude pornography.
"We are not aware of the detailed contents of Mr Coghlan's videos impounded by HM Customs and Excise," Mr Hanley told Mr Cohen. "The material is held by HM Customs and Excise pending destruction."
There would be no changes in the vetting procedures although they had allowed a man of Coghlan's tastes into the diplomatic service, the minister said. "The vetting process cannot claim to be infallible and it relies to a large extent on an individual's co-operation and honesty, supported by the watchfulness of managers and colleagues, rather than on the sort of in-depth and ongoing investigation you may have in mind.
"Such investigation would inevitably be very intrusive and therefore unacceptable in terms of the liberty of the individual and invidious if applied only to members of the Diplomatic Service."
Mr Cohen is planning to protest over the issue in the Commons. He said: "This man has shamed Britain abroad but many people have lost their pensions for much lesser offences. By similar logic, perhaps the Foreign Office should be paying the spy George Blake his pension.
"They've added pornography to the list of prohibited materials for transporting but not to the list of purposes for security vetting. They should tighten up the security vetting."