The Rafah crossing point between Egypt and the Gaza Strip has been reopened hours after a protest by Palestinian police officers forced it to close.
The protest was linked to internal Palestinian tensions
The police, backed by gunmen from the Fatah party, had stormed the crossing, blocking access and forcing European Union monitors to leave.
The monitors have now returned to the reopened border.
The police were protesting at what they see as a lack of government support for their policing efforts in Gaza.
On Wednesday, a UK human rights worker and her parents were kidnapped a short distance away.
The Palestinian Authority took control of the crossing last month after a deal brokered by the US.
Under the terms of the agreement, EU monitors must be present for the crossing to operate.
Julio de la Guardia, a spokesman for the EU monitors, said they temporarily withdrew to the Israeli-controlled border crossing at Kerem Shalom after Palestinian police advised them to leave.
The BBC's Alan Johnston in Gaza says the demonstration was not aimed at the European presence but was a manifestation of Gaza's chronic law and order problems.
There has been a spate of kidnappings, armed takeovers of government buildings, and gun battles in Gaza since Israel withdrew in September after 37 years of military occupation.
On Thursday, a policeman and another man were killed in a clan feud that began when a man was arrested.
Shooting then broke out throughout Gaza, with one gunfight taking place outside the home of Palestinian leader Mahmoud Abbas.
On Wednesday, British aid worker Kate Burton was kidnapped along with her mother and father, who were visiting her.
The three were travelling in a car 200m from Rafah crossing when they were approached by gunmen, police said.
Other Westerners seized in recent weeks have all been released unharmed but after two days without news, this case is causing growing concern.
Palestinian officials say they do not know where the family is and have not heard from the kidnappers.
Protests calling for their release have been held in Gaza.