Two militant groups, the Popular Resistance Committees and the al-Aqsa Martyrs Brigades, claimed joint responsibility for the attack.

It is the latest in a string of recent Palestinian-Israeli clashes.

"This was a joint attack by gunmen who penetrated the Erez crossing and opened fire on the soldiers who were unaware of their presence, causing casualties among the soldiers," a spokesman for the militants said.

The Israeli army did not confirm any casualties.

The Erez checkpoint is the main crossing for thousands of Palestinian workers with jobs in Israel.

On Wednesday the Israeli army killed two gunmen they suspected of trying to plant a bomb near the Karni border crossing. One died at the scene and another in hospital.

Militants have stepped up rocket attacks against Israeli towns from Gaza, while Israel has launched a number of air strikes targeting militants.