Seven security officers at the Defence Procurement Agency (DPA) in Bristol, objected to working with a fellow guard.
He was allowed to return to work last year after being convicted of indecent assault on an eight-year-old girl.
The seven were suspended in November 2003 but dismissed in June for "gross misconduct", the MoD said.
The DPA, based at Abbey Wood in Bristol, said they had been sacked after a departmental disciplinary hearing.
A spokesman told BBC news service that: "We can confirm following a disciplinary hearing into charges of gross misconduct seven members of staff employed at MoD Abbey Wood were dismissed on Friday 18 June."
The dismissed guards were accused of disclosing unauthorised information to the press and harassment of an MoD employee, which they denied.
The MoD spokesman said the convicted man had returned to work in July 2003 after a formal disciplinary hearing concluded there were no grounds to prevent him from carrying out his full duties.
His work would not bring him into contact with children, he added.