The number of contractors dismissed for failing to comply with Shell's health and safety standards or general business principles also fell significantly from 95 in 1997 to 69. In one case the company withdrew entirely from a joint venture because it was unhappy with its partner's ethical standards.
The number of employees among the 100,000-strong workforce sacked for accepting or soliciting bribes fell from 23 in 1997 to three last year, with a further three cases awaiting decisions.
But Mark Moody-Stuart, the Shell chairman, said it was impossible to tell whether this was because the group's tough stand on bribery and corruption was paying off.
He rebuffed suggestions that, despite the reduction in incidents of bribery among Shell staff, the company was still hiding behind contractors who routinely offered bribes in countries such as Nigeria.
Mr Moody-Stuart said Shell would never deal with contractors it knew to be corrupt, but that if it were to impose its own ethical standards on everyone there would be some major oil companies it could not do business with.
He declined to name the joint venture Shell withdrew from, arguing that if it published the identities of all companies it refused to do business with it could run into legal difficulties and possibly challenges from the European Commission.
Last year the company distributed 900,000 "Tell Shell" cards inviting individuals to give their views on the company's ethical performance. It received only 288 replies. Mr Moody-Stuart rejected suggestions Shell had overreacted to criticism relating to events such as the Brent Spar oil rig disposal and the execution of Ken Saro Wiwa in Nigeria.Reuse content