Three women who were part of an aid convoy passing through Libya on the way to Gaza have been sexually assaulted in Benghazi, after a group of five British nationals were briefly kidnapped.

The three women, two of whom are sisters, were part of a large aid convoy travelling to the Gaza Strip. It is thought that they were part of a group of five people who were briefly kidnapped near Benghazi in the early hours of Tuesday and they were released some hours later. The group is currently safe in the Turkish consul in Benghazi and is expected to return to the UK.

Libyan security officials said the attacks happened in the early hours of Tuesday morning. Abdul Barghathi, commander of preventative security in the Libyan defence ministry, said the women had been sexually assaulted, but not raped. "There was no rape, just touching (sexual assault)," he said. "Because there is no British consulate here they were handed to the Turkish consulate." The three women are not badly wounded and are being attended to by consular staff from the UK, he added.

The women were part of a large convoy taking vehicles and aid to the Gaza Strip on a journey that had taken them through France, Spain, Morocco, Algeria, Tunisia and then Libya. It had intended to cross the border with Egypt but was prevented from doing so by Egyptian authorities. The 10-vehicle convoy is still stuck at the border but the five British nationals returned to Benghazi in eastern Libya late on Monday night in order to return home.

The most recent post on the convoy's Facebook page, written on Saturday, detailed the convoy's frustration at being held at the Egyptian border.

It read: "We have been here for five days now. Despite harassment & abuse from the Egyptian authorities here, we're determined more than ever, to persevere in our aim to deliver this aid to Gaza. Well-wishes, prayers & support are appreciated & welcome."

Turkish authorities in London said two sisters and their father, plus another woman and man, were taken near Benghazi on Tuesday and released. "They are at the Turkish consul and they are safe," said a spokesman.

The Foreign Office confirmed that an incident in the city had occurred, but gave no further details. "We are aware of an incident in Libya involving a number of British nationals who were part of an aid convoy and we are providing consular assistance," said a spokesman.

A supporter of the convoy, writing on the All United for Free Palestine page, said five people had been kidnapped, but said that reports in foreign media that two females had been raped were inaccurate. The writer, who did not immediately respond to requests for information, wrote: "If anyone has read or heard a report from Al Watan voice newspaper about the kidnapping in Benghazi of 5 convoy members, the report is partially true in so much as they were taken, however I stress that the report of the two females being raped is not true. All are now safe and being looked after Alhamdulilah."

Benghazi has seen frequent bouts of militia violence in recent months, including the attack by a jihadist militia that killed the US ambassador Chris Stevens at the American consulate in the city, and 18 prominent or retired officials, including the city's police chief, have been murdered in the past 12 months.

Attacks on the British and Tunisian consulates and the attempted murder of the Italian consul in previous months have made the city a no-go zone for most foreigners, with Egyptians on edge after the burning of the city's Coptic church on 4 March.

Benghazi is immune to central government control, its streets controlled by a galaxy of militias, army and police units. Ansar al-Sharia, the Islamic unit blamed for the killing of Stevens in September, is back in its city centre headquarters and defying government demands that it disband.

The burning of the church and arrests of more than 50 foreigners for evangelism have raised tension.