TWO men offered to sell heroin to an undercover police sergeant posing as buyer, the High Court heard yesterday. Hui Kay-pang, 30, and Cheng Ching-man, 40, have pleaded not guilty to a joint charge of offering to traffic in a dangerous drug. Hui has also denied another similar offence, for which he was charged alone. Crown counsel William Lam said that on May 28, 1991, the sergeant was told by his superior about a heroin sale. He was given $440,000 to buy four kilograms of drugs. The officer was introduced to Hui - nicknamed Har Chai (small shrimp) - in a Tsim Sha Tsui hotel coffee shop. But the meeting did not result in a sale. On July 17, 1991, police heard about another sale of six kgs of heroin and supplied the sergeant with $770,000. That evening, the officer met Hui in a Waterloo Road coffee shop. He introduced him to Cheng - nicknamed Lo Kor (older brother) - and during the meeting, heroin was offered for sale, Mr Lam said. The hearing before Mr Justice Stock continues.