* AMCU says members attacked at Sibanye mine
* Fears gold strike may turn violent
* Two-thirds of gold mines not producing (Recasts with AMCU attack claim)
By Sherilee Lakmidas
JOHANNESBURG, Sept 5 (Reuters) - South Africa's AMCU union said seven of its members were attacked at Sibanye's Beatrix gold mine on Thursday, raising fears that an until now peaceful strike in the sector may turn violent.
The strike called by the National Union of Mineworkers (NUM), a rival to AMCU, is now in its second full day. While tens of thousands of NUM members have refused to go underground, the Association of Mineworkers and Construction Union (AMCU) has told its members to report for duty.
"They attacked our members. They were badly assaulted and admitted to hospital," AMCU president Joseph Mathunjwa told Reuters. He said the attacks were on company premises, with some miners attacked in the shower after surfacing from underground.
But a Sibanye spokesman said the company was only aware of one worker who was assaulted while reporting for work and could not say what his union affiliation was.
Sibanye is one of South Africa's four main gold producers.
The NUM was not immediately available to comment. The union, which represents two-thirds of the sector's employees, has been consulting its members on new proposals made by gold producers in a bid to reach a deal.
Hopes the union and management would soon have an agreement over wages helped drive the shares of South African gold producers up more than 3 percent on Thursday. Two-thirds of the country's gold mines have been hit by the strike.
Both sides have been poles apart on the issue of wages with NUM seeking hikes as high as 60 percent for entry-level workers, but it has signalled a willingness to scale back other demands. Two junior producers sealed pay deals with the union's members on Wednesday, agreeing to rises of only about 8 percent.
"The sentiment surrounding the strike has been effectively moderated by deals with smaller producers. It means that the NUM is more amenable and the likelihood of a prolonged strike is no longer there," said David Davis, mining investment analyst at SBG Securities in Johannesburg.
Johannesburg's Gold Index was 3 percent higher by mid-afternoon, led by Africa's top bullion producer AngloGold Ashanti, which was 4.7 percent higher at 141.59 rand. Rival Harmony Gold added over 5 percent and Gold Fields climbed 4.3 percent to 40.95 rand. ($1 = 10.2185 South African rand) (Additional reporting by Olivia Kumwenda-Mtambo; Editing by Ed Stoddard)