ARMED robbers struck at four banks yesterday, escaping with more than $144,300. There have been six bank robberies since Monday, and the matter seems likely to be discussed tomorrow at a meeting of the Hongkong Association of Banks. Yesterday's raids began about 10 am when three men entered the Choi Hung Estate branch of the Standard Chartered Bank and threatened staff with pistols. Two of the men approached different counters and demanded money from tellers before making off with $55,880. About an hour later, the Wing On Bank branch in Lai Chi Kok Road was held up by three men, one armed with what appeared to be a pistol. The gunman threatened the security guard as his accomplices snatched $48,430 and escaped on foot towards Cheung Sha Wan. Shortly before 1 pm, a man with a pistol ran into the Standard Chartered Bank at Container Port Road, Kwai Chung, and was given $10,000 after threatening a 22-year-old female teller. The final raid occurred at 2.14 pm at the Queen's Road West branch of the Standard Chartered Bank when a man, believed to have hidden a gun under a sweater, gave a note to a 38-year-old woman teller demanding $50,000. He was handed $30,000. The Secretary of the Banks Association, Mr Steve Troop, said they would be in touch with police and their members ''fairly soon'' concerning the spate of raids. ''It is possible that we may raise the question of robberies at the weekly committee meeting,'' he said. Crime Prevention Bureau staff officer, Detective Superintendent Graham Lander, said it was too early to predict a rising trend in bank robberies. He said the number of bank robberies fell to 94 last year, a 36 per cent decrease on the 147 reported in 1991. There were 131 cases in 1990. Mr Lander said many of the robberies last year occurred in banks which had done away with bullet-proof glass partitions in preference to customer-friendly open-plan counters. Thirty per cent of local bank branches use such a counter design. ''We were told that some of the banks using the open-plan design were reluctant to change because of corporate pressure for customer friendliness,'' Mr Lander said. ''If they don't change there's not much we can do because the Government does not like to intervene in private business practice or market policy.'' Mr Troop agreed it was a dilemma for banks which wanted a user-friendly and accessible environment for customers on the one hand, while ensuring security on the other. Bank security managers and directors had also been advised by police on procedures to reduce the amount of cash stolen in a robbery. Mr Lander said these methods were proving successful.