GAZA CITY, Palestinian Territories: Gaza's Hamas rulers have arrested two Salafist militants, sources close to the Palestinian Islamist hardliners said Friday, after a Salafist group claimed a rocket attack on Israel.

According to the sources, "the Hamas internal security forces arrested two of our Salafist brothers" in the centre of the Gaza Strip.

A coalition of Salafist groups in Gaza, which oppose the Hamas regime, claimed responsibility for the firing of two rockets at southern Israel on Thursday while US President Barack Obama was visiting the Jewish state.

In a statement headlined "The demolition of Sderot by rocket bombardment in reaction to the visit of the dog Obama," the Mujahedeen Shura Council had said it was responsible for an attack launched from Gaza.

Two rockets hit southern Israel, one landing in the town of Sderot, before Obama travelled from Jerusalem to the West Bank city of Ramallah to hold talks with president Mahmud Abbas, leader of the Palestinian Authority.

Israel retaliated by halving the distance from the shore that Gaza fishermen are allowed to sail and shutting the Kerem Shalom goods crossing from Israel into the territory, a military statement said.

It added that the sanctions would remain in place until the military received fresh instructions from the government.

The relations of the Islamist movement Hamas with hardline groups in Gaza have sharply deteriorated since it violently cracked down on Salafist radicals in 2009.