Sri Lanka has recalled its defence attache in the UK for an inquiry following his offensive act of gesticulating to slit throats of Tamil demonstrators in London, the military spokesman said.

Brigadier Priyanka Fernando, the Military Attache in Sri Lankan High Commission, was seen gesticulating to slit throats of a group of pro-LTTE demonstrators opposite the High Commission office in London on February 4 when the embassy was celebrating the 70th independence day.

He was immediately suspended from work following a video, which showed him behaving in an offensive manner.

However, he was later allowed to resume duties on a presidential directive.

President Maithripala Sirisena directed the authorities to allow him to resume duties but a formal inquiry needs to be done on the incident, military spokesman Brig Sumith Atapattu said.

British politicians who are pro-Tamil urged the British Foreign Secretary Boris Johnson to expel Fernando.

Fernando was hailed a hero by the pro-Sinhala majority nationalist groups for taking on the LTTE rump in the UK and the decision to suspend him was cited as a reason for the government's poor showing in the February 10 local election.

The slit throat incident occurred during a protest held by a group of LTTE supporters outside the High Commission in London on the Sri Lanka's Independence Day.

The protesters demanded information on the missing persons, to release all political prisoners and to close down torture camps.