By Phumza Macanda

JOHANNESBURG, May 9 (Reuters) - The leaders of South Africa's ruling ANC party met labour and Communist allies on Friday for a summit aimed at healing rifts that have emerged under the rule of President Thabo Mbeki.

Investors are spooked by the prospect the ANC could surrender to the left's calls for a shift away from the business-friendly policies pursued by Mbeki's government for the better part of a decade.

Zuma, who became the frontrunner to succeed Mbeki after defeating him for the ANC leadership last year, has vowed to work more closely with COSATU, the largest labour federation, and the small but influential South African Communist Party.

The three are in a formal coalition that has governed since the end of apartheid in 1994.

In a speech at the outset of a three-day summit outside Johannesburg, Zuma praised the ANC-led alliance for showing unity on a wide range of thorny political and economic problems.

"We have spoken in one voice on issues facing our country and continent, be it food and fuel prices, the energy challenge or the crisis in Zimbabwe," said Zuma, cheered by labour for taking a harder line than Mbeki on Zimb +;6