* Islamic State involvement not confirmed by Bangladesh police
* Islamist group says citizens of "crusader nations" not safe
* Britain, Canada also warn against further possible attacks (Recasts with Islamic State statement)
By Ruma Paul
DHAKA, Sept 29 (Reuters) - Western embassies in Bangladesh have restricted the movements of their diplomats, citing "reliable" information that more foreign interests will be targeted after an Italian aid worker was shot dead in an attack claimed by Islamic State.
However, police did not confirm the involvement of the hardline Islamist group, which has ambitions to spread into South Asia. Police in the Bangladeshi capital arrested two suspected recruiters for Islamic State this year.
In a communique translated by U.S. security analysts SITE, Islamic State said a "security detachment" had tracked Cesare Tavella before shooting him with silenced weapons on Monday.
Tavella, 50, was shot in Dhaka's diplomatic quarter by gunmen on a motorcycle. He had arrived in Bangladesh in May, and ran a food security project for ICCO, a Netherlands development group backed by Christian churches. ID:nL5N11Y40W
In its statement, Islamic State hinted at more attacks in Bangladesh and said citizens of what it called "the crusader coalition" were not safe, even in the homes of Muslims.
Attacks on foreigners are rare in Bangladesh, which has suffered a rising tide of Islamist violence over the past year, with four online critics of religious militancy hacked to death, among them a U.S. citizen of Bangladesh origin. ID:nL3N10I43W
The government is fighting to restrain the Islamist groups, who want to turn the Muslim-majority South Asian nation of 160 million into a sharia-based Islamic state.
The U.S. embassy said its diplomats were instructed not to go outside overnight after Monday's shooting and warned of possible attacks on U.S. facilities, citizens and interests.
"In light of the increased threat, U.S. citizens should consider limiting their attendance at events where foreigners may gather, including events at international hotels," it said in a statement late on Monday.
Australia, Britain and Canada also told embassy officials to avoid events where Westerners may gather and warned of possible attacks in "late September".
The motive for Tavella's shooting was unknown, said acting inspector general of police Mokhlesur Rahman.
"But, based on our experience, we can say it is a pre-planned murder," he told reporters after visiting the crime scene in the Gulshan neighbourhood, home to several embassies.
Another police officer investigating the shooting said Tavella's belongings had been left untouched, which appeared to rule out theft as a motive.
Last week, the Australian cricket team delayed its planned departure to Bangladesh after being warned of a potential security risk from militants. The side were due to fly from Sydney on Monday morning for the three-week tour.