The was the uncompromising warning given by Abd al-Aziz al-Rantisi, a senior Hamas political leader, during an exclusive interview with Al Jazeera televison on Wednesday.
He said the releases of the Palestinian detainees were an essential element of the three-month truce agreed last month, and he added: “Hamas would break the ceasefire if Israel did not release all the Palestinian detainees.
“Releasing all the Palestinian detainees was one of the main goals behind announcing a truce. Therefore if all these goals were not achieved, the truce would be cancelled.”
He added: “Sharon keeps escalating Israeli military operations against the Palestinians - in particular seven Palestinians were recently detained in Tobas and Nablus.
“Sharon has violated the truce therefore it will be broken. Sharon is not the only one to decide if the truce will continue or not.”
Al-Rantisi’s comments come at a time of growing tension in the region and uncertainty over whether the ceasefire between Israel and Palestinian resistance groups will hold.
They came a day after the Al-Aqsa Martyrs Brigades, whom Israel wants the Palestinian Authority to disarm, claimed responsibility for the killing of an Israeli civilian on Tel Aviv's seaside promenade.
"There will be more martyrdom operations until the occupation leaves our land," the group said on its website, although leaders of several al-Aqsa cells denied involvement in the attack.
Palestinian Information Minister Nabil Amr said he hoped the stabbing would not affect a truce called by resistance groups on 29 June to halt attacks against Israel.
"We condemn and reject such an act," Amr said.
Rallies urging the release of the
Palestinian detainees continue
However, Israeli Prime Minister Ariel Sharon on a trip to London called on Palestinian Prime Minister Mahmoud Abbas to dismantle and disarm resistance groups.
"There should be a very active struggle - and I would say, I would call it a war - by the new Palestinian government against the terrorist organisations," Sharon said in an address to leaders of the Jewish community in Britain.
There was no immediate Palestinian comment on Sharon's speech, although Abbas has avoided confrontation with the resistance groups, fearing it could trigger a civil war.
Meanwhile, Israeli commandos on Wednesday freed unharmed an Israeli taxi driver kidnapped by Palestinians.
The security forces were led to Eliahu Gurel by two kidnappers arrested earlier in the day. A third was detained while trying to escape during the rescue, the army said.
Gurel went missing on Friday, his cab reportedly found with the engine running in an Arab neighbourhood of East Jerusalem.
No group claimed responsibility for Gurel's kidnapping.
And in another development, Israel plans to deport a Northern Ireland man after failing to uncover evidence supporting suspicions that he was training Palestinians
in bombmaking, Israeli security sources said.
Israel originally thought the man they arrested in the West Bank was a master bombmaker, and had been questioning him about his contacts with Palestinians.
But friends of John Morgan insisted that the man Israel arrested, known in Belfast as Sean O’ Muireagain, was a pro-Palestinian activist with no links to any Palestinian groups.
Morgan's mother Teresa told Israel Radio her son's arrest was a case of mistaken identity. "I understand it was somebody from a different part of the country by the same name," she said. "He is innocent."