At least 15 Palestinians have been killed by Israeli forces in fighting around Gaza a day after the two sides launched talks.
In the deadliest single day of violence in months, militants in Gaza also shot dead a civilian just inside Israel in a sniper attack.
The fighting began a day after a meeting of top Israeli and Palestinian negotiators.
Palestinian president Mahmoud Abbas branded the Gaza operation a 'massacre' and warned that it flew in the face of the peace efforts re-launched at a US conference less than two months ago.
Since the two sides formally re-launched peace talks at the US-hosted conference in late November, some 115 Palestinians have been killed by Israeli fire in Gaza.
Today's operation saw a heavy exchange of fire between soldiers and militants in eastern Gaza City.
Among the dead were ten members of Hamas's armed wing, including the son of Hamas leader Mahmud Zahar.
The identities of the others killed were not immediately known.
About 45 other Palestinians, both militants and civilians, were wounded.
An army spokeswoman said Israeli troops opened fire on a group of armed Palestinians and a car containing gunmen.
Israeli government spokesman Mark Regev said the operation came because of rocket attacks on Israel.
