DHAKA (Reuters) - Islamic State claimed responsibility for shooting a Japanese man in Bangladesh on Saturday, the second foreign national it says it has killed there within a week, and threatened more such attacks.

Police said they had detained four suspects in connection with the shooting of Kunio Hoshi, 65, in Rangpur district, 335 km (210 miles) north of the capital, Dhaka, in an attack similar to the shooting on Tuesday of Italian Cesare Tavella.

“This (Hoshi’s) killing was also carried out by three masked men who came by motorcycle and used a pistol, so the motives may be same,” Home Minister Asaduzzaman Khan told Reuters, before the claim of responsibility.

Attacks on foreigners are rare in Bangladesh. But it has seen a rising tide of Islamist violence over the past year, in which four online critics of religious militancy were hacked to death, among them a U.S. citizen of Bangladeshi origin.

On Saturday, Islamic State warned of more attacks.

“There will continue to be a series of ongoing security operations against nationals of crusader coalition countries, they will not have safety or a livelihood in Muslim lands,” the group tweeted.

Western embassies, the Japanese and South Korean embassies have all issues various warnings for diplomats and citizens to be extra vigilant about their personal security.

U.S. Ambassador to Bangladesh Marcia Bernicat said in a statement that she was saddened by the latest killing.

“I urge the government of Bangladesh to investigate every aspect of this crime and to bring the perpetrators to justice as soon as possible,‎” she said.

One of the four detained people was a rickshaw puller and another was the owner of a residence near where the attack took place, police said.

Security will be increased at foreign diplomats’ and foreign nationals’ homes and workplaces, a high level meeting decided on Saturday, Inspector General of Police AKM Shahidul Hoque said.