South African President Jacob Zuma on Saturday urged unity in a fragile alliance with a key workers' union and communist allies, promising new laws to end casual labour and improve workers' living conditions.

Speaking in Durban to mark May Day, Zuma said that workers' share of national income in Africa's largest economy had not grown to acceptable levels, with rural areas still deeply divided into affluent farm blocs, peri-urban and poorer communal areas.

"The benefits of economic growth have not been broadly and equitably shared," Zuma told a May Day gathering.

Deep divisions between South Africa's ruling African National Congress (ANC), the Congress of South African Trade Unions Cosatu), which has nearly two-million members, and communist allies have threatened a decades-old alliance as rival factions battle for power and influence to shape policy.

Zuma said that the government would introduce laws to promote decent work for all employees, to regulate contract work, subcontracting and out-sourcing in a bid to address labour broking and prohibit some abusive practices

"We are also working to ensure that provisions are introduced to facilitate the unionisation of workers and conclusion of sectoral collective agreements to cover vulnerable workers," he said.

Zuma said that the government was also implementing policies that create an environment for more labour-intensive production methods and procurement policies that support local jobs and build public-private partnerships.

Turning to his allies in Cosatu and the South African Communist Party (SACP), Zuma said that the ruling ANC and its allies needed to be united in order to transform the lives of South Africans.

"There is still a lot that we must do together to advance the interests of workers," Zuma said.

"The ANC is the shield, Cosatu the spear of the workers."

Zuma also reiterated that the FIFA World Cup, due in 39 days in South Africa, will be a resounding success and that it comes as a result of the workers' decades long struggles against minority rule.

"The World Cup is a celebration of our freedom, a celebration of the sacrifices and struggles of our people. Together we will make the tournament a resounding success, because we worked so hard for it over many decades," Zuma said.