A crack army regiment is patrolling the capital's streets at night engaging in surveillance and political work as security tightens before this weekend's Communist Party congress. A report in yesterday's official army paper said the Capital Regional Army was carrying out emergency exercises across the city nightly. 'The 692 regiment has concentrated on training, education and upgrading the political ability of the soldiers,' the report said. 'Units have organised officers to go spying to grasp firmly the situation of the region.' The report in the Quan Doi Nhan Dan does not mention the congress, but comes as more than 1,000 leading communists meet secretly in Hanoi to hammer out policies and leadership changes before Friday's opening. Security has visibly tightened through the week, with all police units mobilised and officers requested not to take leave during the period. Rumours that known agitators are under closer watch have yet to be confirmed, but security forces have been seen at several strategic sites, including the Hanoi television tower. Huge hammer and sickle symbols - rarely seen nowadays - are appearing on many public buildings in preparation. Patrols are also reportedly being stepped up in the southern commercial hub of Ho Chi Minh City. The city is home to many defeated former South Vietnamese soldiers and returning exiles from overseas. Party General-Secretary Do Muoi recently urged continued vigilance in the south, describing it as a 'hotbed' of hostile reactionary movements.