* All four trucker unions agree wage deal - freight bosses
* Three-week strike had caused fuel, cash shortages
* Rand firms after announcement
(Adds rand, details) By Wendell Roelf
CAPE TOWN, Oct 12 (Reuters) - South African truck drivers have agreed a wage deal with employers to end a three-week strike that has hit deliveries of fuel, cash and consumer goods in Africa's biggest economy, the Road Freight Employers Association (RFA) said on Friday.
More than 20,000 truck drivers have taken to the streets in often violent protests since late September, demanding higher wages. At least one person was killed and dozens of trucks were torched by demonstrators.
"The parties have signed an undertaking that they agree to a three-year industry wage agreement which is to be signed at approximately 10 a.m. (0800 GMT) on Friday," the RFA said in a statement.
All four transport unions were part of the agreement, RFA spokeswoman Magretia Brown-Engelbrecht said, although she did not reveal details of the deal.
The rand , which fell to a 3-1/2 year low on Monday due to concerns about transport and mining strikes, firmed to a session high of 8.61 against the dollar shortly after the news.
Moody's also cut South Africa's government credit rating last month, citing the government's failure to tackle the industrial unrest that has swept from the platinum and gold sectors into other parts of the economy.
The South African Transport and Allied Workers Union (SATAWU), which represents the majority of truck drivers, said it was still consulting its members on the proposal and would communicate its decision at the meeting with employers.
Petrol stations have been experiencing delays of up to a day in getting fuel and some have run completely dry, the South African Petroleum Industry Association said on Thursday.
Other affected companies include logistics groups Imperial Holding , Super Group , Grindrod , Barloworld and Bidvest .
Since August, almost 100,000 workers across South Africa, including 75,000 in the mining sector, have downed tools in often illegal and violent strikes that undermined investor confidence and already shaky economic growth.
More than 50 people have been killed in labour-related protests in the last two months, including 34 shot dead by police at Lonmin's Marikana platinum mine on Aug. 16.
South Africa is home to 80 percent of known reserves of platinum and the price of the precious metal has risen more than 20 percent since the Marikana shootings, the bloodiest security incident since the end of apartheid in 1994.
Striking gold miners rejected the industry's latest wage offer on Thursday. Africa's top three bullion producers - AngloGold Ashanti , Gold Fields and Harmony Gold - have given them until Monday to reconsider.
(Additional reporting and writing by Agnieszka Flak; Editing by Ed Cropley)
Keywords: SAFRICA STRIKES/TRUCKS