Unions and employers in South Africa have sealed a deal to end a three-week-long truck drivers' strike.

"We are very very pleased to announce that a settlement has been reached,"  Dave Behrens, the truckers' representative, said on Friday afternoon.

"This three-year agreement secures stability in the industry for a long time to come."

The deal has ended weeks of road freight paralysis enforced by some 20,000 truckers. The strike had reportedly threatened the supply both of consumer goods and gas in Africa's largest economy.

Some trucks were set on fire during the strike. Drivers were attacked with petrol bombs and rocks, with at least one fatality.

As details of the agreement emerged, the Road Freight Employers Association announced a return to work.

"The agreement has been signed by everyone. The strike is off immediately," said the union's Penwell Lunga.

All four of the country's transport unions were part of the deal.

Workers agreed to accept wage increases of ten per cent from March 2013, eight per cent the following year and nine per cent for 2015. They had been demanding a 12 per cent pay raise.

"This will bring great relief for many people in South Africa," said Al Jazeera's Tania Page, reporting from Johannesburg.

"Food prices had been pushed up due to the strike. This period - in the build up to Christmas - should be an important time of the year for business."

News of Friday's wage deal has also eased pressure on the South African Rand. The currency, which tumbled to a three-year low on Monday, rallied to its highest in a week following the announcement.

The country has been gripped by labour unrest since August, when platinum miners in Marikana staged a series of strikes demanding higher pay. 

In a violent confrontation, the like of which has not been seen since the end of apartheid in 1994, police shot and killed 34 striking miners and wounded dozens more. 

Almost 100,000 workers across the country subsequently downed tools, both in solidarity with the Marikana miners, and demanding improvements in their own pay and conditions.

Finance agency Moody's cut South Africa's credit rating in September, citing the government's failure to tackle the industrial unrest that shook investor confidence amid sluggish economic growth.