TUNIS (Reuters) - The number of foreign tourists visiting Tunisia fell sharply again in the first half of this year, official data showed on Monday, a day after the North African nation marked the first anniversary of an attack by an Islamist gunman who killed 38.

The gunman killed his victims, mostly British holidaymakers, on a beach in the resort of Sousse on June 26, 2015, in an attack that dealt a heavy blow to Tunisia's tourism industry, which accounts for eight percent of national output.

That attack came three months after gunmen killed 21 tourists at the Bardo National Museum in the capital Tunis.

Islamic State militants claimed both attacks.

The Tourism Ministry data showed the number of foreign tourists fell by 21.5 percent in the first six months of 2016 compared to the same period last year.

The number of foreign tourists fell to 1.82 million in the Jan-June period from 2.32 million in the same period last year. The number of British tourists slumped to just 8,000 from 190,000 in the first half of 2015.

Tourism is a key source of foreign currency and jobs for Tunisians, who overthrew veteran ruler Zine El Abidine Ben Ali in a 2011 uprising that brought democracy to the country.

Last year tourist arrivals fell to 5.5 million, the lowest level in decades, after several European tour companies and cruise operators suspended operations in the wake of the Sousse attack.

Tourism Minister Salma Elloumi Rekik told Reuters last month Tunisia expected to attract 5.5 million foreign tourists this year, about the same as last year, after increasing security at hotels and focusing on new markets.

(Reporting By Tarek Amara; Editing by Gareth Jones)