Former US President Jimmy Carter, who is leading a delegation monitoring Egypt's first post-revolt presidential election, said on Saturday the process was "encouraging" despite unprecedented constraints.

"I would say that these (elections) have been encouraging to me," he told a news conference in Cairo, but added that his Carter Centre had "constraints placed on us as witnesses that have never been placed on us before."

He said his delegation was not allowed to see collation at regional stations.

"There is no way we can certify that the entire process was proper," Carter said.

But in general "there was no pattern reported... that showed that the procedure favoured a particular candidate," he said, describing any violations as "haphazard."

Carter was speaking after landmark presidential elections on May 23 and 24 to choose a successor for former president Hosni Mubarak who was ousted by a popular uprising in February last year.

The election seals a tumultuous military-led transition marked by political upheaval and bloodshed.