A top Hamas security official was arrested at Cairo airport for using falsified travel documents, Egyptians officials said Sunday.

Mohammed Dababish's relatives said he was returning from a pilgrimage to Saudi Arabia when he was stopped.

Dababish is a top official in Hamas' internal security unit, which oversees intelligence matters in Gaza. Hamas officials declined to comment.

Egypt has arrested a string of Hamas figures since one of its soldiers was killed in a border shooting early this year, including the son of a Hamas Cabinet minister last month.

Egypt believes a Hamas sniper was responsible for the shooting.

Dababish's name was on a wanted list for using falsified travel documents to enter and leave the country, the officials said, speaking on condition of anonymity because of the sensitivity of the subject.

He was also questioned about an illegal shipment of walkie-talkies interdicted by police in Sinai apparently destined for Gaza, they added.

Egyptian security forces are on high alert in the Sinai Peninsula bordering Gaza and Israel because of information about possible Palestinian rocket attack from Egypt toward Israel.

Egyptian officials have blamed Hamas for a deadly rocket attack last month on Israel and Jordan's Red Sea port of Aqaba that killed one person and wounded four. Hamas has denied the accusations.

Egypt is also investigating reports of plans to smuggle rockets from Gaza into Egypt and then launch them back toward Israel, said officials. So far, no rockets have turned up.

The officials say hundreds of police and private agents been deployed along the border, at entry points to Sinai and along checkpoints.