South Sudan's military has gained 'full control' of the strategic oil town of Malakal, after days of fierce fighting with rebel forces, the government has said.

Army spokesman Philip Aguer said troops loyal to President Salva Kiir had "completed their control of Malakal town" after several days of fighting during which "whole enemy force was destroyed".

Inside Story - South Sudan's forgotten crisis

However, he also said defence chiefs had "ordered a hot pursuit to track down the rebels wherever they may be heading from Malakal".

There was no immediate reaction from the rebels, who attacked the town 10 days ago after a pro-government militia leader defected to the rebels.

South Sudanese government forces launched a major assault on rebel-held areas in the north in late April, in what has been described as one of the heaviest offensives in the 17-month long civil war.

The town, already in ruins after repeated clashes in December 2013, is the state capital of Upper Nile and the gateway to the country's last remaining major oil fields.

The fighting has cut off over 650,000 people from aid, with gunmen accused of torching towns, raping residents and looting relief supplies, according to the United Nations and aid agencies.

The African Union has demanded sanctions and an arms embargo be imposed on South Sudan's warring leaders. While Washington's envoy to the UN, Samantha Power, has said the US was working with the Security Council to gather evidence for possible sanctions.

Violence in the world's youngest nation has been characterised by rape, attacks on civilians and medical facilities and ethnic massacres.

Fighting broke out in December 2013 when President Kiir accused his former deputy Riek Machar of attempting a coup, setting off a cycle of retaliatory killings across the country.

Tens of thousands of people are believed to have been killed since the country gained independence from Sudan in 2011.

Source: Al Jazeera and agencies