Two close protection officers were injured in an attack on a convoy carrying the British ambassador to Libya in Benghazi on Monday.
The Foreign Office said all other staff were safe and had been accounted for. It is working with the Libyan authorities to find out who was behind the attack, a spokesman said.
The Foreign Office would not say whether the injured security personnel were British.
"A convoy carrying the British Ambassador to Libya (Dominic Asquith) was involved in a serious incident in Benghazi this afternoon," a spokesman said.
"Two close protection officers were injured in the attack. All other staff are safe and uninjured.
"We are working with the Libyan authorities to establish who was responsible for the attack."
Details of the incident were sketchy but reports suggested the vehicle carrying the security detail was hit by a rocket-propelled grenade.
It was the latest in a recent series of attempts to target diplomatic personnel in Benghazi, where last year's uprising against Muammar Gaddafi's regime took hold.
Last week the US diplomatic mission in the city had a bomb thrown at its front gate and the offices of the Red Cross were hit by a rocket-propelled grenade last month.
In April, a convoy carrying the head of the UN mission to Libya was targeted with a bomb.