NATIONAL Mutual Asia, Hong Kong's only listed insurance company, which has been plagued by a smear campaign, yesterday said that most of its agency managers had agreed to stay with the company. The company, which shot into the limelight with the sudden resignation of its chief executive Andrew Yang Fan-shing 10 days ago, said that about 85 per cent of its agency staff would remain in its employ. The commitments came after National Mutual, whose share price slipped on news of the controversy, gave the agency managers until last Friday to commit themselves to staying with the company. Unsigned notices were sent to some newspapers, including the South China Morning Post, claiming that half of National Mutual's sales force of 3,500 were resigning in support of Mr Yang, who said that he was leaving for Australia while rumour had it thathe would join a rival company. National Mutual is suing Mr Yang and three other executives, accusing them of conspiracy to harm the company.