JUBA - The head of the UN peacekeeping mission in South Sudan has called for an end to fighting in the country, and for peace talks to be given a chance.

Hilde Johnson told the BBC the humanitarian situation was worsening.

At least 1,000 people have died since fighting erupted last month between supporters of President Salva Kiir and those of his sacked deputy Riek Machar.

Both sides have sent delegations to talks in Ethiopia but so far the rebels have not agreed to end hostilities.

There are reports that heavy fighting is continuing in the key town of Bor on Wednesday.

What began as a power struggle between Mr Machar and President Kiir has taken on overtones of a tribal conflict. The Dinka, to which Mr Kiir belongs, are pitted against the Nuer, from which Mr Machar hails. ”Violence has been committed by both sides. Unfortunately, elements on both sides have exploited the situation and have fuelled ethnic tension,” Ms Johnson told the BBC’s James Copnall in Juba.

She said the conflict had its roots in "a political struggle that needs a political solution” and called for "a major effort of national reconciliation” to address the historical reasons for current divisions.

Talks between the two sides in Ethiopia are due to begin on either Wednesday or Thursday.

Mr Kiir confirmed on Wednesday afternoon that a 14-member delegation had left for Ethiopia.

Observers say the discussions are likely to be complicated, as the two sides will have to agree on a mechanism to monitor a ceasefire.

Mr Kiir has already ruled out any power-sharing arrangement with Mr Machar in the longer term.

Mr Machar claimed his delegation would be headed by Rebecca Nyandeng, the widow of John Garang, who led South Sudanese rebel forces against Khartoum for many years - though she later denied this in a BBC interview.

As a Dinka, Ms Nyandeng would help Mr Machar challenge the allegation that his rebellion is primarily from his Nuer ethnic group.

Mr Machar’s forces are a mix of mutinous soldiers loyal to him and an ethnic militia called the "white army”, known for putting white ash onto their bodies as a kind of war-paint and insect repellent. East African leaders have been leading mediation efforts to end the crisis. On Monday, Uganda’s President Yoweri Museveni threatened the rebels with military action if they failed to agree to a ceasefire by the end of Tuesday.

It appears that the pressure on Mr Machar worked, says the BBC’s James Copnall in the capital Juba, as the rebel leader appears to be sending a delegation despite Mr Kiir failing to agree to demands such as the release from jail of Mr Machar’s political allies.

But Mr Machar insists he will not order his troops to stop fighting before preliminary talks have taken place.

South Sudan is the world’s newest state. It was formed in 2011, gaining independence from Sudan after decades of conflict.

Agencies