JOHANNESBURG – South African platinum producer Lonmin is laying the groundwork to restart its operations next week after a concerted effort to woo striking miners back to work by taking its latest wage offer directly to them.

This points to a possible end game in the 15-week strike by the Association of Mineworkers and Construction Union (AMCU), the longest and most costly ever for South Africa's mines, which has also hit Anglo American Platinum and Impala Platinum.

Wage talks collapsed two weeks ago and the trio of companies - the world's top producers of the precious metal - have been trying to undermine AMCU's leadership with direct appeals to the strikers, betting that they are keen to return after going so long without pay.

"Our shop stewards are saying that Lonmin management has been going around this week to all the shafts to prepare for the start up on the 14th," an official with a rival union to AMCU told Reuters.

Lonmin has been asking its employees through a text messages and other means to indicate if they want to accept the latest offer and return to work and the company has said it should know by Friday if it can go ahead with the May 14th start.

In an internal memo sent to its employees last week which Reuters has seen, the company spelled out the steps to be taken through the vote, providing an SMS number and an e-mail address where they could send their responses.

The letter said employees had until Thursday, May 8 at 16:00 local time to send their replies.

"If we have sufficient take-up, a reminder SMS will be sent and logistics will be arranged in terms of transport and security provisions around return to work," the memo said.

"The safety and security of our employees remains our number one priority and additional security will be in place during and immediately after this start-up period."

Security will be regarded as crucial as the companies say AMCU is using violence and intimidation to keep its members in line, allegations the union has denied.

A toll-free Help Line number is also provided for workers who want to ask questions about the offer.

One problem acknowledged by industry sources is that many of the striking miners will not be able to afford air time for their cell phones and much of the labour force has also returned to home villages far from the shafts in areas such as the Eastern Cape province.

Implats said on Thursday it was conducting an SMS vote on the offer late this week.

The companies are offering increases of up to 10% that they say would raise the overall minimum pay package to R12 500 a month by July 2017, including cash allowances such as for housing.

AMCU had initially demanded an immediate increase to R12 500 in the basic wage, excluding allowances, but softened that stance in March to staggered increases that would amount to R12 500 within three or four years - still a third more than what the companies are offering in basic salaries.