* Workers are on student visas, unwilling to speak out-lawyers
* 7-Eleven investigating abuse allegations (Adds details, clarifies that investigation centres on abuse at franchises)
By Colin Packham
SYDNEY, Sept 21 (Reuters) - Efforts to compensate allegedly underpaid workers at 7-Eleven convenience stores in Australia will fail without a visa amnesty for affected staff, lawyers said on Monday.
Australia's 7-Eleven Stores Pty Ltd, which is licensed by U.S.-based 7-Eleven Inc SILC.UL , has appointed an independent panel to investigate allegations its franchisees underpaid staff or forced them to work longer hours without compensation.
But Giri Sivaraman, principal at legal firm Maurice Blackburn representing the workers, said many of the affected staff were on student or other visas and feared being deported if they spoke out. Many Australian student visas prohibit holders from working more than 20 hours a week.
Sivaraman said complainants would need to provide evidence, including rosters, time sheets and bank statements to prove their claim, but in doing so they could also show they broke visa rules.
"They don't trust the company and are concerned they will be reported for working more than 20 hours a week when, in fact, they were often coerced into doing this," Sivaraman said.
Maurice Blackburn was representing nearly 100 complainants although thousands of current or former 7-Eleven staff could be affected, a source with knowledge of the legal process said.
The probe by the Australian firm comes as the convenience store chain, which is ultimately owned by Japan's Seven & i Holdings Co 3382.T , is facing accusations of unfair treatment of its franchisees in North America.
A spokesman for 7-Eleven said the company did not immediately have a response to the statements by Maurice Blackburn.
Russ Withers, chairman of 7-Eleven Australia, said in a statement earlier this month that the company would compensate any staff affected.