Organizers of mass marches on Gaza's border with Israel have moved protest tent camps dozens of meters (yards) closer to the border fence, heightening the risk of more bloodshed.

Protesters led by Gaza's ruling Hamas pitched five tent camps last month as gathering points for Friday marches.

Organizers say the camps will gradually move toward the fence until May 15, but have made conflicting statements about a possible mass breach.

Israel says it will prevent a border breach at all costs. In three weeks, Israeli troops shot and killed 28 Palestinian protesters.

On Thursday, five tents in a camp near Gaza City were moved to within 300 meters of the fence and bulldozers raised a new protective berm. At another camp, earth mounds were moved as a new camp boundary.