Occupied Jerusalem: Israel's secret service has declined to assist US agents guarding former US President Jimmy Carter during a visit in which Israeli leaders have shunned him, US sources close to the matter said on Monday.

Carter angered the Israeli government with plans to meet Hamas's top leader, Khalid Mesha'al, in Syria, and for describing Israeli policy in the occupied Palestinian territories as "a system of apartheid" in a 2006 book.

American sources close to the matter said the Shin Bet security service, which helps protect visiting dignitaries and is overseen by Olmert's office, declined to meet the head of Carter's Secret Service security detail or provide his team with assistance as is customary during such visits.

"They're not getting support from local security," an American source said.

Another source described the snub as an "unprecedented" breach between the Israeli Shin Bet and the US Secret Service, which protects all current and former US presidents, as well as Israeli leaders when they visit the United States.

Israel has also rejected Carter's request to meet jailed Palestinian uprising leader Marwan Barghouthi, who is seen as a possible successor to President Mahmoud Abbas, a spokesman for Carter said.