Libyan government forces are continuing to battle Islamic State (Isis/Daesh) militants in Sirte. Reuters photojournalist Goran Tomasevic has been accompanying the fighters as they advance towards the centre of the city. His latest photos show them using a Soviet-made tank to bombard IS positions from a beach on the Mediterranean coast.

Battle for Sirte Libya
A fighter of Libyan forces allied with the UN-backed government fires a Soviet-made T-55 tank towards Islamic State positions from a beach in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
A fighter carries a 122mm tank shell on a Soviet-made T-55 tank in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
A member of forces loyal to the UN-backed Libyan government paddles in the sea during a break in the fighting in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
Government-backed fighters take a break on the beach in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
Libyan forces operate their Soviet-made T-55 tank on a beach in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
A member of Libyan forces allied with the UN-backed government fires a T-55 tank at Islamic State fightersGoran Tomasevic/Reuters

Libyan commanders say a few hundred Islamic State fighters are now encircled in the centre of Sirte, though they have retained control of four neighbourhoods.

US air strikes are helping in the fight to clear Islamic State from the militant group's North African stronghold. Libya's UN-backed government requested the strikes nearly three months into a campaign that had slowed because of heavy casualties from sniper fire, mines and mortars.

The Pentagon said the first targets of the strikes included tanks, construction and military vehicles and a rocket launcher. The strikes were carried out by Marine Corps AV-8B Harriers from the USS Wasp, an assault ship located in the Mediterranean Sea, and by armed drones piloted from Jordan. In addition, intelligence-gathering drone flights were being operated from Sigonella air base in Sicily.

Sirte, on Libya's Mediterranean coast about halfway between Tripoli and Benghazi, has been controlled by Islamic State since February 2015, becoming its most important base outside Syria and Iraq, and its loss would be a major setback for the group. They are already under pressure from US-backed campaigns in both Syria and Iraq.

Battle for Sirte Libya
A fighter allied with the UN-backed government holds a bunch of grapes as he fires a rife at Islamic State militants during a battle in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
A fighter of Libyan forces allied with the UN-backed government runs for cover during a battle with Islamic StateGoran Tomasevic/Reuters
Battle for Sirte Libya
A fighter of the Libyan forces allied with the UN-backed government...Goran Tomasevic/Reuters
Battle for Sirte Libya
... is carried away when he is woundedGoran Tomasevic/Reuters
Battle for Sirte Libya
Another government-backed fighter is carried out the areaGoran Tomasevic/Reuters
Battle for Sirte Libya
A member of forces loyal to the Libyan government gestures as heavy artillery is fired towards Islamic State positions in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
A government-backed fighter shows a disarmed anti-personnel mine planted by Islamic State militants in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
Government-backed fighters run for cover during a battle with Islamic State in SirteGoran Tomasevic/Reuters
Battle for Sirte Libya
Libyan government-backed fighters take cover as pieces of bricks fly off the wall after Islamic State militants opened fire at themGoran Tomasevic/Reuters
Battle for Sirte Libya
Government-backed fighters take part in a battle against Isis in Sirte, LibyaGoran Tomasevic/Reuters