A magazine editor has made an unprecedented apology over the publication of a "star letter" which called for diamonds polished in Israel to be labelled "blood diamonds".

Retail Jeweller magazine, published by Emap, was withdrawn from the Baselworld Jewellery Fair in Switzerland last month because of concerns about the letter from Irish Palestinian Solidarity campaigner Sean Clinton.

The letter claimed that rough diamonds polished in Israel should be classified as "blood diamonds", and that revenue from the Israeli diamond industry provided £622m a year for the IDF.

This month, editor Laura McCreddie published a retraction saying: "We very much regret that in this instance we have inadvertently allowed our pages to be used to advance a political agenda.

"The letter has caused consternation to a number of our readers with its references to Israel's diamond trade and the efficacy of the Kimberley Process. The letter was the personal opinion of the correspondent and not that of Retail Jeweller but its publication has undoubtedly caused offence to many readers, which we very much regret."

Harry Levy, vice-president of the London Diamond Bourse, and three other prominent industry figures, met Ms McCreddie to discuss the concerns of Jewish and Israeli jewellers. He said: "I had never heard of a specific plan to target diamonds from Israel. But these people will just target anything from the country. I hope now that Emap will send the editor to see the Israeli diamond industry."

All Israeli diamonds are certified by the Kimberley Process, which guarantees them to be "conflict free", where proceeds do not finance rebel movements aimed at undermining legitimate governments.