A port operator at the Kwai Tsing Container Terminals is seeking an injunction to force hundreds of dockers back to work as their strike for a pay rise entered its fourth day. The workers' union said it was "completely wrong" to solve the dispute through the courts and pledged to continue the strike until their demands were met. Gerry Yim Lui-fai, managing director of Hongkong International Terminals, which operates five of the nine terminals, said: "I've signed legal documents today. The application for an injunction takes time and requires the approval from the court, but we'll do it for sure." The company is a subsidiary of billionaire Li Ka-shing's Hutchison Whampoa. Yim said an injunction was necessary for safety reasons because protesters had allegedly stormed one of the contractor's offices. Yim had warned on Saturday that the operator "would not tolerate any long-term action at the terminal". Stanley Ho Wai-hong, of Union of Hong Kong Dockers, denied that any strikers were involved in the damage, but said they remained committed to their cause. "If they think they can stop the strike through legal channels, they are completely wrong," Ho said. "No matter what tactics they use, our determination won't be weakened." About 450 dockers - up from about 300 on Saturday - were picketing a terminal roundabout yesterday as negotiations with the contractors employing them remained stalled. The workers are seeking a 17 per cent pay rise. The operator said its contractors raised salaries by 5 per cent this year and that workers should be making HK$21,000 per month. The union said the industrial action had caused a serious operations slowdown, with 80 to 90 per cent of business interrupted. But Hongkong International Terminals said the impact had been minimal. Yim said the impact was eased after dozens of workers returned to work, but he admitted there were concerns that traffic could be jammed after the Easter holidays. Although different workers' unions, including Cathay Pacific Airways Flight Attendants Union, had voiced support for the strike, some container truck drivers complained that their income had fallen in the past days because of the strike. "If the cargos go to other ports, then we'll have less work to do and our income will drop," said Tse Long, vice-chairman of Container Transportation Employees' General Union. He said he hoped the strike would end soon. The striking dockers plan to march from Wan Chai to the government headquarters in Admiralty today to urge the Labour Department to set up negotiations. The department said it would follow developments and assist in talks between the two sides. It hoped that both could solve the problem in a calm and rational manner.