The Rafah crossing between southern Gaza and Egypt was closed on Sunday, a Palestinian official told AFP, saying Egyptian officials had left the border following the spiralling political unrest.
Razi Hamad, head of the crossing within Gaza's Hamas government, said the border would most likely be shut for "several days" while admitting that it would depend on developments in Egypt, where violent protests have entered their sixth day.
He said the Egyptian forces had apparently left their post at some point on Friday or Saturday when the crossing is closed for the weekend, as a wave of massive anti-government protests swept through the country.
In Gaza City, the Hamas-run interior ministry issued a statement saying the situation on the Egyptian border was "quiet" and that there were no problems there.
But an official in Rafah told AFP Hamas had bolstered its forces along the border, with hundreds deployed along the frontier compared with the normal deployment of around 50.
Hamas has so far given no official reaction to the developments in Egypt, where more than 100 people have been killed in the biggest demonstrations to sweep the country in more than 30 years.
Protesters are demanding the removal of Egyptian President Hosni Mubarak who has ruled the country since 1981.