People gather at the site of a cargo plane crash, on a small island in the White Nile river, close to Juba airport, in the Hai Gabat residential area. AFP

AFP/Juba

At least 36 people were killed on Wednesday when a Soviet-era Antonov plane crashed just after take-off from South Sudan's capital Juba.

Police and rescue workers recovered the bodies of men, women and children among the wreckage of the An-12 cargo plane, which crashed into a farming community on an island in the White Nile river, seconds after departure.

"So far 36 bodies have been collected and brought to hospitals," South Sudan Red Cross official Majju Hillary told AFP, adding that all the victims were on board the ill-fated aircraft. 

Two survivors were pulled out of the twisted metal hulk of the plane but one later died, leaving a young boy the only survivor, the Red Cross said, adding the number of dead could still rise.

"We can't assess this is the final toll, as some debris is too heavy to be lifted and needs some heavy machinery," Hillary added.

The five-member Armenian crew were all killed, the Armenian foreign ministry said in a statement.

Ukraine-based Antonov said in a statement that the "An-12B was is no state to fly because it failed to undergo timely technical servicing ... that should have included work on extending its resources and exploitation timeframe."

 'Landed near my door'

Farmer Ibrahim Mohamed said the plane went down near his home, scattering debris around his hut.

"The sound was so loud... the plane started descending and landed near my door," Mohamed told AFP.

"One of the tyres broke off and ran into the house -- but thank God it did not injure anyone," the father of four said.

Cargo planes serving remote parts of South Sudan often carry passengers as well as goods, and are commonly overloaded.

The main fuselage of the plane ploughed into thick woodland but the debris was scattered over a wide area around the riverbank, according to an AFP reporter at the site.

Radio Miraya, a United Nations-backed station, said the plane had been heading to the northern Upper Nile state, crashing some "just 800 metres from Juba International Airport runway."

Police said they did not know how many had been on board the plane when it crashed -- nor if anyone had been killed or injured on the ground -- and so were unable to give an official death toll.

Large chunks of metal were scattered across the island, which is home to several small farming communities.

The UN peacekeeping mission, which is based close to the airport, said it was aiding the search and recovery operation, and had sent ambulances and troops to the rescue.

Juba's airport is the busiest in the war-torn country, which is the size of Spain and Portugal combined but has only a few paved roads.

The airport hosts regular commercial flights, as well as a constant string of military aircraft and cargo planes delivering aid to remote regions cut off by road.

Sudan was plunged into a civil war in December 2013, when President Salva Kiir accused his former deputy Riek Machar of planning a coup, setting off a cycle of retaliatory killings that has split the poverty-stricken country along ethnic lines.

Fighting continues despite an August peace deal, but the current battles are taking place far from the capital.

UN-backed experts have warned of the "concrete risk of famine" if the fighting, which has killed tens of thousands of people, continues, and aid does not reach the hardest-hit areas.