A feared assassination attempt against Tony Blair forced him to cancel a visit to the Gaza strip.
Israeli sources said defence minister Ehud Barak advised the former prime minister to stay away from the Hamasruled coastal territory as he could be targeted for attack, according to a Jewish news agency.
Mr Blair's office said there had been a "specific security threat" which could have endangered the local community, as well as the visiting dignitaries.
Tony Blair was due to visit Gaza but cancelled after a security threat
He had been due to make his first trip to the Hamas-controlled area as the representative of the Middle East "Quartet" - the US, UN, EU and Russia.
His team is understood to have been aware from last night of the threat, believed to be from a local group - not Hamas - and turned round at the border.
Mr Blair was not due to have met any Hamas leaders but the Islamist movement, which seized control of Gaza in June 2007 from forces loyal to Palestinian president Mahmoud Abbas, had set up checkpoints and banned cars in areas he was to tour.
Hamas blamed Israel for forcing Mr Blair to cancel his trip. "The Israeli occupation exerted great pressure to prevent Tony Blair from visiting the Gaza Strip because they did not want him to see the size of the disaster caused by the unjust blockade," said Hamas spokesman Taher al-Nunu.