South Sudan troops trying to recapture the oil hub of Bentiu from rebels have been forced back amid heavy gunfire, a BBC correspondent says. Government troops advanced towards the town centre over the weekend with an armoured column. But the BBC’s Alastair Leithead, who is in the UN compound on the outskirts, saw a contingent of troops in retreat. The town has changed hands several times since fighting broke out in South Sudan last December. Tensions came to a head after President Salva Kiir accused his sacked deputy, Riek Machar, of plotting a coup. Rebel forces deny UN charges that they killed hundreds of peoplealong ethnic lines after seizing Bentiu in April.