"Everyone asks me to strengthen Abu Mazen, but I tell them, not at the expense of Israeli lives," Sharon, using the popular name of Palestinian President Mahmoud Abbas, was quoted by a senior government official as telling a cabinet meeting.
Israel freed 500 jailed Palestinians on 21 February as part of a pledge to release 900 prisoners in a goodwill gesture towards Abbas, who declared a ceasefire along with Sharon at a summit in Sharm el-Sheikh, Egypt, on 8 February.
But Sharon, speaking ahead of ministerial-level talks with the Palestinians later in the day on the prisoner issue, set new
conditions for a release, amid media reports that 400 men might go free soon.
"Let it be clear, there will be no prisoners release before steps are taken against terror," a senior government official quoted Sharon as telling the cabinet.
"The Palestinians are doing nothing about this issue. It would be a mistake of the first order to make even the smallest concession on security. We cannot give them the opportunity to wage a continuous campaign of fire towards Jewish communities."
Sharon said Abbas had to move
against resistance fighters
Palestinian chief negotiator Saeb Erekat said Sharon's comments showed Israel had frozen the implementation of confidence-building understandings reached in Sharm el-Sheikh.
"It's clear that the only thing that is not frozen is the continuation of settlement activities, the (West Bank) wall and non-compliance with a cessation of violence," Erekat told Reuters.
Israeli occupation forces have killed at least 20 Palestinians, 10 of whom have been children, since the Sharm el-Sheikh ceasefire in February.
Security handover frozen
Stressing a commitment to Israeli security in the face of
opposition to the pullout from settlers and their supporters,
Sharon has said there could be no talks on Palestinian statehood until Abbas disarmed fighters as a US-backed "road map" demands.
Israel also has frozen the handover of more West Bank cities to Palestinian security control after accusing the Palestinian
Authority of failing to disarm fugitives in two towns
transferred in March.
The Israeli official said Sharon had instructed cabinet minister Tsipi Livni to convey his terms when she met Palestinian Prisoner Affairs Minister Sufian Abu Zeideh.
Israeli forces have killed 10
children since 8 February
Abu Zeideh, speaking to Israeli Army Radio, said he would press Israel to release long-serving prisoners, including those convicted of attacks against Israelis before the signing of interim peace deals in the early 1990s.
Livni in an interview with Israel Radio said the government would continue to oppose the release of "prisoners with blood on their hands".
In March, Abbas persuaded resistance groups to agree to a "period of calm" until the end of the year, and attacks against Israeli targets dropped sharply.
Jewish settlements illegally built in the Gaza Strip and communities in southern Israel have come under sporadic rocket and mortar bomb fire by resistance fighters, who either did not sign on to the de facto truce, or said they were retaliating for Israeli attacks on Palestinian civilians.
Under a plan to "disengage" from conflict with the Palestinians, Sharon intends to evacuate all 21 Jewish settlements in the Gaza Strip and four in the West Bank this summer.
Abbas, while pledging an "iron fist" against ceasefire violators, has said he wants to co-opt rather than confront resistance groups to avoid civil strife.