Israeli warplanes raided the northern Gaza Strip Monday after militants fired rockets over the border, as Israel prepared to free a new batch of long-term Palestinian prisoners.

It was the first air strike on Gaza in more than two months and came shortly after two rockets were fired at southern Israel.

Israeli officials said the flareup along the Gaza border -- which has been quiet for months -- was unlikely to affect the prisoner release due to take place on Tuesday night as part of US-brokered peace talks with the Palestinians.

Witnesses said the air strike targeted a training ground west of Beit Lahiya that was used by militants from the armed wing of Gaza's ruling Hamas movement.

Hamas slammed the Israeli raid as "an escalation which aims to terrorise... our people," adding that it held Israel "completely responsible for any effects or deterioration."

Neither the air strike nor the earlier rocket attacks on southern Israel caused any damage or casualties.

The Israeli military said the air force had struck "two concealed rocket launchers" in northern Gaza following a cross-border attack.

Earlier on Monday, militants fired two rockets at the southern Israeli port city of Ashkelon, one of which was shot down by the Iron Dome missile defence system, the army said.

And on Sunday, a mortar shell was fired over the border that also caused no damage or injuries. In September, there were two instances of rocket fire, but Israel did not respond.

Monday's Israeli air strike was the first since August 14, when the air force hit targets in the same area, also in response to rocket fire.

That attack occurred just hours after Israel released a first batch of 26 Palestinian prisoners in line with commitments which led to a resumption of direct peace talks in late July, following months of sustained US pressure.

Gaza fire 'won't delay' prisoner release

But Monday's exchange of fire along the Gaza border was not expected to affect plans to free a second batch of prisoners, with a senior official telling AFP it "won't delay" the release of the 26 inmates.

The list of prisoners slated for release, 21 from the West Bank and five from Gaza, was approved on Sunday.

The names were published later that night, giving victims' families and groups 48 hours to mount a legal challenge before the release goes ahead.

All but one of the prisoners were arrested before the signing of the 1993 Oslo peace accords, which won the Palestinians limited self-rule but failed to bring about an independent state.

All were convicted of killing Israelis, according to the details published by Israel's prison service.

A Fatah official told AFP that 19 of the prisoners set to be freed were members of the group, which is led by Palestinian president Mahmud Abbas, while four belong to the Popular Front for the Liberation of Palestine (PFLP) and three to Hamas.

Some 2,000 Israelis, including an ultra-nationalist minister, protested outside the Ofer military prison near Ramallah on Monday chanting "Death to terrorists!" and holding pictures of Israelis killed in attacks.

Meir Indor, head of Almagor, a group representing Israeli victims of Palestinian attacks, had earlier told AFP his organisation would be petitioning the high court against the impending release.

The Israeli army meanwhile said Monday that it had arrested 10 West Bank-based members Hamas overnight, while Palestinian officials put the number at 15.

Hamas condemned the arrests, saying they were a joint Israeli-US-Palestinian plot aimed at forcing through any agreement reached in the peace talks, which the Islamist group opposes.

Israeli Prime Minister Benjamin Netanyahu had pledged to release a total of 104 Palestinians in four stages in line with commitments which brought about a resumption of talks on July 30 after a hiatus of nearly three years.

Netanyahu reiterated on Monday at a meeting of his ruling rightwing Likud party that "we must take into account the weight of reality" and fulfil those commitments to release prisoners.

Israeli public radio quoted International Affairs Minister Yuval Steinitz as saying: "We can't say yes to the Americans one day, and three months later say no."

Last week, an Israeli official said that in parallel with the release, a new batch of tenders would be announced for construction in settlements in the West Bank and annexed east Jerusalem, in a move allegedly coordinated in advance with Washington and the Palestinians.

The Palestinians have adamantly denied any such link, saying further settlement construction threatens the peace talks.