A senior Hamas leader has described as a declaration of war an Israeli plan to set new borders unilaterally by annexing Palestinian land.
The militant group's political leader in exile, Khaled Meshaal, told the AFP news agency the plan was intended to meet only Israel's security needs.
Mr Meshaal said the plan would not bring about peace.
Acting Israeli PM Ehud Olmert said he planned to set permanent borders for Israel within four years.
But he said he would give Hamas time to reform, disarm and embrace past interim peace agreements before pursuing a unilateral solution.
Hamas, which won elections in January, is in the process of forming the next Palestinian administration.
‘Israel's unilateral disengagement from the Palestinian territories is a declaration of war against the Palestinian people,’ Mr Meshaal told AFP.
He said the plan would ‘permit Israel to stay in the largest section of the West Bank, to maintain their wall and settlements, to refuse all concessions on Jerusalem and to reject the Palestinians' right of return’.
Mr Meshaal said that Mr Olmert was ‘in the process of committing the same errors toward the Palestinians that [Israeli PM Ariel] Sharon did’.
Mr Olmert, whose ruling centrist Kadima party is leading in the polls ahead of the 28 March election, outlined his disengagement plan in an interview with the Jerusalem Post newspaper on Thursday.
He said that as part of such moves, Israel would build more Jewish settlements on occupied Palestinian land between Jerusalem and its largest settlement, Maaleh Adumim.
Palestinians say the Maaleh Adumim plans would cut East Jerusalem off from the West Bank and wreck their aim of establishing a Palestinian capital in Jerusalem.
Deadline
Correspondents say the four-year deadline is the first timescale set by an Israeli leader for what is expected to be a large-scale pullback from parts of the West Bank.
Mr Olmert took over the Israeli government after Ariel Sharon suffered a stroke in January and he has promised to carry on Mr Sharon's work.
Mr Sharon pulled Israeli settlers and troops out of the occupied Gaza Strip in 2005 as part of a unilateral plan that circumvented stalled negotiations with the Palestinians.
The US has said borders between Israel and the Palestinian territories should be determined through negotiations with the Palestinians and has warned Israel not to annex parts of the occupied West Bank.
The international community considers all settlements in the West Bank, including East Jerusalem, as illegal under international law, though Israel disputes this.
Israel says the West Bank barrier is designed to stop suicide bombers from entering, but Palestinians see it as an attempt to grab West bank territory.
The International Court of Justice issued an advisory ruling in 2004 that the barrier breached international law where it is built on occupied territory and should be dismantled.