(REUTERS) -- South Africa's mine workers union on Tuesday said it had rejected a revised wage offer from platinum miner Lonmin Plc on Tuesday, paving the way for strike action.

The National Union of Mineworkers said it was demanding an 11 percent wage rise and Lonmin was offering 9 to 10 percent over two years, depending on the category of the workers within the company's grading structure.

The NUM rejected these on the basis that it may be prepared to accept the offer provided that the 10 percent is extended to category 4 for both years, the union said in a statement.

The union wanted the wage rise to be back-dated to July 1 while the company said it should be effective from Oct. 1.

The next stage before legal strike action can take place will be for both sides to try and iron out their differences with a government mediator.

A strike at Lonmin could have a significant impact on global platinum supplies given the company's third-place ranking in world production. The miner is targeting sales in 2012 of 750,000 platinum ounces.

Its bigger rivals Impala Platinum and Anglo American Platinum reached agreements earlier this year with South African unions but had to cough up above inflation wage increases over the next two years which ranged from 8 to 10 percent.

The union said it was also demanding 2,000 rand ($240) housing allowance for across the board whilst the company offers 1,850 for year one and 1,950 for year two.

The union said it would meet with its members on Thursday for further discussions.