The Government said the threat of religious disharmony and chaos justified the use of the Internal Security Act last week in the biggest police sweep since mass arrests of members of the Al-Arqam Islamic sect three years ago. Ten men were arrested under the provisions of the act, which allows for detention without trial for those allegedly involved in 'suspicious activities which could disrupt national security and unity among Muslims in the country'. They included two former opposition figures, 80-year-old Abdullah Hassan, who was a supporter of Parti Islam se-Malaysia and of Al-Arqam until it was disbanded, and Paharuddin Mustapha, 73, who was associated with Parti Rakyat Malaysia 20 years ago. Their offence was to practise and preach the teachings of the Shi'ite sect, which is banned in Malaysia, where Muslims have traditionally been Sunnis. Abdul Hamid Othman, a minister without portfolio in the Prime Minister's Department, said Shi'ite teachings opposed Malaysia's constitutional monarchy and its government. He said the danger posed by the men arrested had 'reached a serious level' as they were beginning to adopt a militant approach. 'If we allow these movements here, the country might face religious problems such as those in Middle East countries,' he said. Analysts said the Government was likely to be concerned over any resurgence of Shi'ite activity with economic problems on the rise and mainstream Sunnis divided between conservative followers of Islamic officials and supporters of the reformist Prime Minister, Dr Mahathir Mohamad. But human rights groups have condemned the use of the Internal Security Act.