An Israeli air strike wounded two Palestinian militants in the southern Gaza Strip Thursday, medical and security sources said.

"Two Palestinians were hit and injured by an Israeli drone while they were riding on a motorbike east of Khan Yunis," Gaza's Hamas-run health ministry spokesman Ashraf al-Qudra told AFP.

Palestinian security sources described the two as "militants," without saying to which group they belonged.

The army confirmed the strike, saying it had "intercepted terrorists during their final preparations to launch rockets towards Israel."

The strike came after three mortar rounds were fired at Israeli troops along the southern border fence, causing no injuries or damage, it said.

The armed wing of the leftist Democratic Front for the Liberation of Palestine (DFLP) it was responsible "for the firing of two mortar shells at an (Israeli) military position."

Several hours after the mortar fire, Israeli warplanes carried out another strike, hitting a training camp for militants from the radical Islamic Jihad movement in the southern border city of Rafah, witnesses said.

No one was injured.

The army confirmed the second raid, saying it had struck a "terror site in the southern Gaza Strip" linked to the earlier mortar attack.

On Wednesday, an Islamic Jihad militant was killed near Gaza City in what medics and family said was an Israeli drone strike, but the army denied any involvement.

In recent weeks, tensions have risen in and around Gaza after a year of relative calm, with five people killed since December 20. Four of the victims were Palestinian and one was Israeli.

More than a dozen Palestinians have also been wounded over the same period by gunfire or in Israeli air raids on targets in the territory.