Hamas's exiled deputy leader said on Thursday the group could be forced to negotiate directly with Israel, ahead of planned talks in Cairo to consolidate a truce.

But an Israeli minister dismissed any possibility of talking directly with the Islamist movement, whose charter calls for the destruction of the Jewish state.

Hamas itself later reiterated its policy was not to talk with Israel.

Hamas does not recognise Israel, and Israel denounces Hamas as a "terrorist" organisation, and the two sides have never had any direct contact.

Following weeks of indirect, Egyptian brokered negotiations, Israel and Hamas agreed to halt their fire in Gaza on Aug 26 after 50 days of war, their deadliest confrontation in years.

The indirect talks are set to resume mid-September to discuss longer-term issues.

Asked if Hamas would contemplate negotiating directly with Israel, Mussa Abu Marzuq, the movement's exiled deputy leader, said it might be needed.

"If the situation remains as it is now... Hamas could find itself forced to do this," he told the Palestinian Al-Quds TV, referring to the dire humanitarian situation and continued blockade on Gaza.

Under terms of the truce deal, Israel pledged an immediate easing of restrictions on goods and construction materials being shipped in to Gaza, but so far, officials say there has been little change on the ground.

"From a legal (Islamic) perspective there is nothing wrong with negotiating with the occupation," he said, indicating it could be necessary in order to guarantee the "rights" of the people of Gaza.

"Many of the issues that have been taboo within the movement could be up for discussion," he said of Hamas's historic refusal to negotiate with Israel.

But Israel's Science Minister Yaakov Peri dismissed outright any possibility of negotiating directly with Hamas.

"As long as Hamas doesn't abandon the path of violence and terrorism, recognise Israel and the Quartet conditions, Israel will not conduct direct talks with this terrorist organisation," Peri told public radio.

The conditions of the Middle East Quartet include recognising Israel, renouncing violence and respecting past agreements between Israel and the Palestine Liberation Organisation.

"We will conduct indirect talks with Hamas through Egypt, but will do so in different rooms," Peri said, describing the way the Gaza truce talks were run over the past two months.

Hamas later reiterated that "talking with the Zionist enemy is not the policy of the movement."

"Nor has it been put forth for discussion," it said in a statement.