The decision -- described as a provisional measure -- comes after the country's Sonntagszeitung newspaper published a photograph of one such device taken by a reporter shadowing rebels in the town of Marea, north of Aleppo, at the end of June.
While uncertainty remains about how or even if Swiss grenades are being used by Syrian rebels in their fight against government forces, all arms shipments to United Arab Emirates have been put on hold, the State Secretariat for Economic Affairs (SECO) said.
"Although the evidence remains unclear, SECO has immediately moved to freeze all arms export permits to the UAE," spokeswoman Antje Bärtschi told AFP.
"We took this matter seriously because something similar happened last year when a journalist covering Libya found crates of Swiss munitions in Libya. These crates were exported by a Swiss company to Qatar which signed a non re-export agreement. It was an error on Qatar's part."
Initial findings by the Swiss authorities indicated that the grenade in question was indeed of Swiss origin and was made by Ruag, an arms manufacturer based in Bern, and originates from a shipment made by Ruag to the United Arab Emirates in 2003.
A total of 225,162 hand grenades were exported to the armed forces of the United Arab Emirates, according to the Federal Department of Economic Affairs (FDEA).
As part of the export deal, the UAE signed an agreement not to re-export the munitions anywhere else, the FDEA said.
"As far as the FDEA is aware, the hand grenade ... originates from a Ruag shipment to the United Arab Emirates in 2003. At present there is no evidence that Swiss hand grenades have found their way to Syria," said the government statement.
"Inquiries are ongoing however."
Ruag, which is present at a total of 14 sites throughout Switzerland, told the newspaper that the grenade in question "looked like a Ruag product".
In its statement the FDEA said arms shipments from Switzerland to Syria stopped after the War Material Act was signed in April 1998. Doubt also remains about whether the photograph was taken in Syria, it said in the statement.
"The indications received from the press raise a number of questions: it is unclear, for example, why there are no photos of the location at which the hand grenade was found."
Describing the arms shipment freeze as "provisional", SECO has also recalled existing unused arms export licences.
"A decision regarding further reaching measures can only be taken once the facts of the matter have been sufficiently clarified," it said in a statement.