A Swiss laboratory has discovered traces of pork in seven out of twenty tests carried out on kebabs sold in several of the country's cities, local Muslim authorities announced Monday, expressing shock about the finding.

"Sample analysis show a very low proportion" of pork meat, or less than 0.1 percent, the Swiss Central Islamic Council (CCIS) said in a statement.

Islamic tradition forbids the consumption of pork.

The group said it believes the traces of pork are the unintentional result of gaps in the production process, saying equipment used to handle the meat may have been used to also manufacture the kebabs.

CCIS staff said they were "shocked" by the discovery deriving from random tests carried out in Basel, Biel, Geneva, Kreuzlingen, Lausanne, Lucerne, Winterhur and Zurich.

The organisation ordered the test sampling after being "alarmed by the scandal that recently erupted in Germany where seven percent of pork meat was found in meat for kebabs."