Chief Executive Donald Tsang Yam-kuen is expected to explain to executive councillors today the case in which a lawmaker helped Tsang's sister-in-law get compensation for losses on Lehman Brothers minibonds. He may also give a public explanation of the case. Tsang returned to Hong Kong from Japan last night after taking four days' leave over the holiday weekend. Lawmaker Abraham Razack helped Lam Suk-jing, Tsang's sister-in-law, recover 60 per cent of her investment three months before most other minibond investors were made an offer. The news has triggered claims of favouritism. Norman Tsang Yam-huen, Lam's husband and the chief executive's brother, has said there is no link between the compensation and his family ties. Chief Secretary Henry Tang Ying-yen also said the chief executive had stated at a government meeting that he had a relative who had bought Lehman Brothers products. The latest controversy comes after Tsang faced criticism over a cash coupon initiative in his policy address to encourage the use of energy-saving light bulbs. That move stands to benefit the business of his elder son's father-in-law. Democratic Party chairman Albert Ho Chun-yan said he did not see anything unusual in the latest case. 'I don't see that the chief executive could pressure bankers to take actions and I don't see why the bankers would have supported him,' Ho said. The party wrote to Tsang last week, calling on him to give details of the light-bulbs case to the legislature, but has no plan so far to ask him to explain the minibonds case to lawmakers. The Civic Party said it also did not see sufficient grounds to accuse Tsang of favouritism. But League of Social Democrats lawmaker Albert Chan Wai-yip said: 'The government has to tell the public whether any officials have been in contact with bankers. Did Donald Tsang demand any officials do something for his family member?' Lawmaker Raymond Ho Chung-tai, chairman of the Legco subcommittee investigating the sale of Lehman Brothers products, said he had yet to receive any requests from subcommittee members to discuss the latest row in forthcoming meetings. The Alliance of Lehman Brothers Victims, which represents many minibond holders, is planning to stage a demonstration on Sunday to protest against the alleged favouritism. Another group of investors holding Lehman Brothers equity-linked notes will stage an overnight sit-in outside the Legislative Council building next week. Peter Chan Kwong-yue, chairman of the alliance, urged the chief executive to clear doubts before the latest controversy escalated. Hong Kong investors lost billions of dollars on minibonds guaranteed by Lehman Brothers when the US investment bank went bankrupt in September 2008. Minibonds are not corporate bonds, but high-risk, credit-linked derivatives.