Canto-pop singers Jill Vidal and Kelvin Kwan Chor-yiu could remain in detention in Japan for at least two more weeks after suspected prohibited drugs were found in their luggage. Vidal's music label, Amusic, said last night the detention period for the troubled star would be extended by 14 to 23 days because Japanese police had begun investigating the drugs allegedly found in their luggage. The pair were arrested for cannabis possession in Shibuya, Tokyo, on February 24. An expert in Japanese law said they might face drug trafficking charges. An Amusic spokeswoman said the label was notified of the detention by its lawyers in Japan, but the police had not specified whether Vidal or Kwan's luggage had contained the suspected prohibited drugs. She did not disclose whether charges had already been filed, but said the Japanese law-enforcement agencies would make their decision when the investigation of the luggage was completed. Duncan Wong, the head of Kwan's record company, Universal Music Hong Kong, said he had spoken to Kwan's parents yesterday morning, but they were still waiting for information from lawyers. Hong Kong barrister Shahmim K. Khattak, who is familiar with Japanese law, said Vidal and Kwan might face a charge of drug trafficking because Kwan had reportedly admitted he brought cannabis from Hong Kong. If they were deported by Japanese authorities, they might be arrested by Hong Kong law-enforcement agencies. The Japanese police had the right to detain suspects for 23 days after arrest. Suspects who wanted to plead guilty to minor offences could opt for a summary trial within this period. The case would proceed to court within 14 days of the decision to opt for summary trial, so the maximum detention period for a suspect in a criminal case was 37 days. Mr Khattak said Japan's criminal compensation law allowed a suspect to ask for compensation if police lacked enough evidence to proceed or the charge was dismissed. The compensation for being held in detention ranged from 1,000 to 125,000 yen (HK$79 to HK$9,840) a day. On Saturday, Amusic said marijuana and unspecified other substances had been found in one of three tests on Vidal's urine. The label's spokeswoman said last night Vidal's urine was clean in the third round of the tests, but she did not say when the tests were taken or when the urine samples were collected. Vidal is said to have remained calm in detention, but to have exclaimed 'Oh my God!' when presented with coverage of the case in Hong Kong newspapers.