Eight dead in ship accident.(File Picture: Mass Communication Specialist 2nd Class Joshua Fulton/U.S. Navy via AP, File)

The U.N. migration agency says eight Tunisian migrants have died and a further 20 are missing after a Tunisian naval ship collided with a migrant boat.

Flavio Di Giacomo of the International Organization for Migration said Monday that about 45 others were saved in a joint Maltese-Italian operation.

The Tunisian defense department said in a statement that the collision happened Sunday about 54 kilometers (30 miles) off the coast of El Ataya, on the island of Kerkennah. The circumstances remain unclear.

Di Giacomo said the number of Tunisians making their way from Tunisia to Italy is on the rise, although the reasons are not clear. IOM estimates that 1,400 Tunisians arrived in Italy last month, compared with 1,357 in the first eight months of the year.