THE Labour Department is reviewing the minimum wage paid to Hong Kong's 120,000 foreign maids, but workers' groups say they fear their claim for a pay rise will be rejected for the second successive year. The Asian Domestic Workers Union (ADWU) has planned a rally and march in Central next Sunday to pressure the Government into granting a 20 per cent claim, which will see their minimum monthly wage rise by $600 to $3,800. It will be the second march this year to press for better pay and working conditions by foreign maids, who also want more protection built into their contracts and the abolition of the so-called two-week rule. In confirming the review yesterday, a department spokesman said the level of wages paid to local domestic helpers or Chinese amahs - who have no minimum rate of pay - would be a key consideration. Though neither the department nor the Census and Statistics Department could provide figures on earnings for local amahs, the Hong Kong Confederation of Trade Unions (HKCTU) said they were much lower than for foreign maids. ''It's only an excuse for not increasing the salary for [foreign] domestic helpers,'' HKCTU executive secretary Winnie Tam Pik-yan said. The HKCTU and the ADWU have urged the Government to make inflation its sole consideration in the review, and say a comparison between foreign maids and local amahs would be unfair. ''The Chinese local amahs stay with employers for more than 20 to 30 years - they are treated as part of the family - and they [the department] should not compare us with them,'' said ADWU chairman Remy Borlongan. The union had, in a meeting with labour and immigration officials early this month, sought to lift the minimum wage from $3,200 to $3,800 - in line with an inflation rate of about 10 per cent for each of the past two years. The Government last increased the wage of foreign maids in September 1991. The department says it reviews the wage annually. Ms Borlongan said foreign maids had more living expenses than local amahs and needed to send a substantial amount of their earnings to families in their home countries, where inflation rates were often worse than in Hong Kong. ''They should not forget us,'' she said, adding that she expected about 1,000 foreign maids to attend the rally at Chater Garden, before a march to Labour Department offices in Pier Road. Ms Tam said that, unless the minimum wage was lifted, foreign maids' living standards would continue to drop. ''All we want to do is to maintain the living standard,'' she said. ''Some of them work continuously for 14, 16 and 20 hours a day,'' she said. The department spokesman said a decision on the minimum wage would be announced by early next month. Inflation would be only one of the review's many considerations. ''We have to take into account many things for consideration and the wages of the local maids is one of them,'' he said.