By Vuyani Ndaba JOHANNESBURG (Reuters) - Whether ratings agencies will cut South Africa's rand-denominated debt to junk status split economists in a Reuters poll, just three days before an announcement that could trigger a selloff in local bonds and currency. Downgrades to sub-investment grade could trigger forced selling of up to $12 billion of South African bonds and put more pressure on the rand. Fitch has already downgraded ratings of debt priced in foreign and local currency to junk status. S&P Global has cut only the foreign debt rating and Moody's is still one notch above sub-investment grade in both cases. Thirteen of 25 economists surveyed on Monday said at least one of the major agencies would cut the local currency rating to junk on Friday. The other 12 said there won't be a downgrade. If both S&P Global and Moody's cut local currency ratings to junk, South Africa will be ejected from Citi's World Government Bond Index (WGBI). "Following the medium term budget policy statement which did not deliver on fiscal consolidation, avoiding credit ratings downgrades on Friday has become less likely," wrote Annabel Bishop, a chief economist at Investec. However, South Africa is set for a potential game-changing period in coming months and credit agencies may wait. Kim Silberman, an economist at Standard Bank, said because the outlook is based on the African National Congress leadership conference next month, it may make sense for agencies to wait until after the conference to make a decision. "Three months just takes you past the February budget, allowing ratings agencies to make a more informed decision after the elective conference," Silberman said. Economists suggest the rand could fall five percent and benchmark 10-year bond yields rise 50 basis points immediately after a cut to junk for the local rating. However, they indicated it is hard to say just how much bonds and the rand would sell off. Ejection from the crucial bond indexes means passive investors mandated to invest in local bonds would automatically have to withdraw from those investments. Agencies normally announce reviews after markets have closed, so Monday could be a busy morning for markets. (Editing by Larry Kign)