Facebook is embroiled in a row with a group of British activists who say it is "censoring" material that might offend the Turkish government.

Three activists – 27-year-old student Rosa Gilbert, pro-Kurdish rights campaigner Mark Campbell, and British Kurd Ari Murad – all say Facebook unfairly removed posts that they insist did not breach community standards.

Posts they say were deleted include images of graffiti and protest signs accusing Turkey of oppressing the Kurdish minority in the country.

The social media giant confirmed a number of posts had been deleted in accordance with its community standards that ban references to terrorist organisations, in this instance the Turkey-based Kurdish militia group PKK.

It also admitted to removing some posts in error that have since been reinstated, though declined to give detail on what these were.

But the tension between Facebook's users and its moderation policy highlights the tightrope it faces in balancing freedom of expression with moderating content deemed illegal in other countries.

It also shines a spotlight on Turkey's laws and how these apply internationally. In Turkey, where it is illegal to insult the president, the government has faced heavy criticism for blocking social media sites in times of political unrest.

Facebook's own internal data, published biannually, shows a significant increase in requests from Turkish authorities last year asking it to make content restrictions – the same year Turkey temporarily banned Twitter and YouTube after users spread allegations of government corruption.

Turkey is among a number of countries, including the UK, the USA, and India, that makes thousands of such requests each year, but it appears to have a high level of success in persuading Facebook to translate those requests into action.

The latest figures show a 137% increase in Facebook making "content restrictions" in response to requests from Turkish authorities in the first six months on 2015 compared to the same period in 2014.

Between January and June 2015 Facebook made 4,496 content restrictions in response to requests from Turkey. The number appears high when compared with the number made in response to the UK, which managed just eight content restrictions over the same period.

Many of the Facebook restrictions, as outlined below, related to "criminal cases" in regard to the Turkish law 5651, which enables the country to block terrorism-related content as well as content featuring crime and drugs.