* Planned march may be show of force
* Sides remain poles apart on wages
* Companies have lost $615 mln in revenue so far
By Ed Stoddard and Zandi Shabalala
JOHANNESBURG, March 3 (Reuters) - South Africa's Association of Mineworkers and Construction Union will stage a march in Pretoria on Thursday, dimming prospects for a swift resolution to a five-week strike at the world's top three platinum producers.
The announcement came as talks continued between the Association of Mineworkers and Construction Union (AMCU), and mining companies Anglo American Platinum (Amplats), Impala Platinum (Implats) and Lonmin under the auspices of a government mediator.
The strike has affected more than 40 percent of global production of platinum, used for making emissions-capping catalytic converters in automobiles. South Africa accounts for about 70 percent of global output.
The union and the mining companies remain poles apart on the issue of wages, with AMCU demanding a more than doubling of basic entry-level pay to 12,500 rand ($1,200) a month under the populist battle cry of a "living wage".
The union said in a statement that its members would march to the seat of South Africa's government, the Union Buildings, to present a "memorandum" to President Jacob Zuma, several cabinet ministers, and the "platinum bosses".
The strike, the latest in a series to hit the mining sector, is an unwanted distraction for the ruling African National Congress party ahead of general elections in May.
Industry sources say AMCU, at mass meetings last week, indicated it planned to bus in thousands of its members for the march, which suggests they expect to still be on strike.
AMCU did not disclose the nature of the memorandum but said it would hold a news briefing about the march on Tuesday. The union often uses marches and rallies to flex its muscles in displays of force to show it retains rank and file support.
The mining companies have said they can ill afford the wage increases being demanded given the backdrop of depressed metals prices and rising costs and have offered pay hikes of up to 9 percent, well above the current inflation rate of 5.8 percent.
Since the strike began, the companies say they have collectively lost more than 6.6 billion rand ($615 million) in revenue, according to a chamber of mines' website which constantly updates the losses (http://www.platinumwagenegotiations.co.za/latest-news/2014).
About 10,000 ounces of production is being lost per day which would mean 305,000 ounces as of Monday, based on 30.5 working days having been lost since the strike began.
BROKEN RIBS AND ARMS
Violence has also marred the stoppage.
In the latest reported incident, the National Union of Mineworkers (NUM), which is not part of the industrial action, said one of its members had been assaulted by striking miners as he tried to go to work on Monday morning at Amplats' Union Mine.
"William Nkoebele who is a winch operator at Union Mine suffered serious head injuries, broken ribs and broken arms," NUM said in a statement.
An Amplats' spokeswoman confirmed that a contract employee had been assaulted on Monday on his way to work at the mine but could not say what his union affiliation was.
AMCU emerged as the top union on the platinum belt after poaching tens of thousands of NUM members in a vicious turf war that killed dozens of people in 2012 and triggered sovereign credit downgrades for Africa's largest economy.
In another development, local media reported that a new union has formed on the platinum belt, the Workers Association Union (WAU), which is opposed to the strike and claims around 8,000 members.
Implats' spokesman Johan Theron said the company was aware of the new union but its membership numbers remained unchanged.
Striking AMCU members would have missed their monthly pay cheques last week and so the stoppage may be testing rank and file resolve, especially as the typical South African miner has several dependants to feed.
According to the companies, employees have lost close to 3 billion rand in earnings to the strike so far. ($1 = 10.7417 South African rand) (Editing by Susan Fenton)