Royal & Sunalliance (RSA) staff sacked over the exchange of pornographic emails started their internal appeals against dismissal on Tuesday.

About ten staff have been fired, and more still may go, over the exchange of lewd emails that have been described as far more offensive than just an X-rated Bart Simpson image.

The scandal started at the Liverpool office on December 15, when a doctored cartoon image of the famous rascal was brought to the attention of RSA bosses by a recipient outside the company.

At the time RSA suspended around 40 staff and began quizzing up to 100 others.

Public relations manager Mike Wallwork would not reveal how many staff had now been sacked and how many suspended pending further investigation, although newspaper reports have put the number of sackings at ten.

Wallwork said he could not reveal the number because more staff, mainly at the Liverpool and London offices, may be dismissed or disciplined as the case unfolds.

He said the case involved emails far more offensive than the rumoured Bart Simpson image. Newspaper reports have said the images included a picture of Muppets characters Kermit the Frog and Fozzie Bear having sex.

“It isn't just about a distasteful Bart Simpson image, it's about other images that are unacceptable by any standards,” Wallwork said.

“We did issue company guidelines on the June 1, 2000, on acceptable and unacceptable use of email and the internet and said that they would be rigorously enforced.”

Wallwork would not say when the investigation would be completed.

“It's ongoing,” he said. “I couldn't draw a line in the sand.”