Switzerland has suspended all arms exports to the United Arab Emirates following reports that Swiss-manufactured hand grenades - intended solely for shipment to the Gulf state - had shown up in Syria.

The Swiss government said the decision was taken on Wednesday, and all existing unused arms export licences had been recalled. Officials described it as a “ provisional measure” pending the outcome of an investigation which was already underway.

The move follows publication of a photograph in Switzerland’s Sonntagszeitung newspaper last Sunday which purported to show a Swiss-made grenade in the hands of Syrian rebels operating in the town of Marea, north of Aleppo, at the end of June.

The newspaper said the photograph, which apparently did not show the location it was taken in, was taken by one of its reporters who had been sent to the town to make contact with rebels fighting forces loyal to the Syrian regime

Government officials in Berne said that although it remained unclear whether Swiss grenades were being used by Syrian rebels, all arms exports to the United Arab Emirates had been put on hold. “The State Secretariat for Economic Affairs has immediately moved to freeze all arms export permits to the UAE,” a spokeswoman said.

It is not the first time that Swiss weapons initially exported under agreement to friendly Arab states have shown up in politically embarrassing locations. Crates of Swiss munitions were discovered at a location in Libya during fighting in the country last year. The crates were found by a journalist covering the conflict.

The Swiss government has since insisted that the crates were first exported to Qatar which had signed an agreement banning their re-export and that the blame for the munitions’ arrival in Libya was Qatar’s alone.

In the Syrian case, Switzerland’s initial findings have revealed that the grenade in question was made by the Bern-based weapons manufacturer RUAG and that it was exported to the UAE as a regular arms shipment back in 2003. RUAG has admitted that the grenade in the photograph “looks like” one of their products.