Khaled Meshaal, who is based in Damascus, told the AFP news agency in an interview that "Israel's unilateral disengagement from the Palestinian territories is a declaration of war against the Palestinian people".
The head of the militant group that won a surprise victory in elections in the Palestinian territories on 25 January denounced acting Israeli prime minister Ehud Olmert's plans to fix Israel's permanent borders by 2010 through unilateral withdrawals from the West Bank.
"This is not a peace plan, but a war declaration, which will 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."
"It is a unilateral disengagement by Israel in the interest of its security needs and not the demands of peace," said Meshaal, whose group refuses to recognise Israel's existence and has carried out dozens of attacks against the Jewish state.
"Olmert is in the process of committing the same errors toward the Palestinians that (Ariel) Sharon did."
"It is a unilateral disengagement by Israel in the interest of its security needs and not the demands of peace"
Hamas political chief
Olmert, whose ruling centrist movement dominates opinion polls for Israel's election in three weeks, unveiled his plans in interviews with the Jerusalem Post and Haaretz newspapers, published on Thursday.
He said he envisaged the borders would include the West Bank settlement bloc of Gush Etzion, the Ariel region of settlements in the north, the "Jerusalem envelope", Maale Adumim and the "Jordan River as a security border".
He described his plan as aimed at preserving a Jewish majority population in Israel.