Colombo, Aug 14, SPA -- Sri Lankans mourned the death of slain Foreign Minister Lakshman Kadirgamar Sunday as investigations into his assassination continued following the arrest of 15 minority Tamils, dpa quoted the police as saying. Over 100 people were questioned in connection with the slaying. Some of them are possible witnesses who may have seen the attackers escaping. The capital city was placed under tight security as foreign dignitaries were expected to attend the state funeral on Monday. Norwegian Foreign Minister Jan Petersen, accompanied by Deputy Minister of Foreign Affairs Vidar Helgesen and Indian External Affairs Minister Kanwar Natwar Singh and Defence Minister Pranab Mukherjee confirmed they would attend the funeral ceremonies. Separate security operations continued overnight to search houses in the city for possible suspects connected with the assassination or their accomplices. In operations carried out until Sunday noon at least 16 people, 15 of them minority Tamils, were arrested, but police were yet to confirm whether they had any direct link with the assassination which took place at the minister's private residence in Colombo. The minister was shot by a sniper from a building overlooking his residence. Kadirgamar was coming out of his swimming pool when he was shot. Investigators have so far identified the sniper's location, where they found a grenade launcher, but not the murder weapon. The country's police Inspector General Chandra Fernando said evidence found so far suggested that the Tamil rebels of the Liberation Tigers of Tamil Eelam (LTTE) were responsible for the attack. Tamil rebels have strongly denied the allegation and instead said that "Colombo, ridden with internal rifts and power struggles, should look inwards for culprits of the assassination." --mor 1250 Local Time 0950 GMT www.spa.gov.sa/282976