CONGESTION on the roads leading to Kwai Chung port has caused Hongkong's largest terminal operator to accuse another of not taking enough preventative measures to avoid it. Hongkong International Terminals (HIT) has criticised Sea-Land Orient Terminals (SLOT) for allowing vehicles heading for its terminal to obstruct the road leading to HIT's facilities. HIT managing director John Meredith said SLOT was not doing enough to stop the congestion. ''Last year, during the debate to secure the Terminal 9 project, the huge traffic queue leading to Sea-Land miraculously disappeared,'' he said. ''And now that the Terminal 9 issue has been resolved, the queue is back there again.'' SLOT officials could not be contacted for comment. Mr Meredith said it was unfair that HIT's efficiency should be affected by this after it had invested heavily in parking areas for its customers. As long as the Government allowed queuing on the roads leading to the terminals, this situation would continue, he said. Mr Meredith said the problem was compounded by SLOT having shipping lines as shareholders, so they could not send their containers to other terminals. Mr Meredith also reiterated his call for the Government to provide back-up land behind container terminals 7 and 8, warning that the congestion on roads leading to Kwai Chung would worsen without more facilities. HIT, which handled 60 per cent of Hongkong's container throughput, had spare capacity and was growing at a rate of more than 20 per cent a year, he said. Terminal facilities at Kwai Chung are expected to come under great pressure this summer as business increases with Guangdong. After dynamic growth of 19.5 per cent in 1992, the province is forecast to equal or improve on that performance this year. Mr Meredith said HIT had approached the Government for back-up land.