(Adds Misrata fighting)
* Rebels take casualties in battle for Brega
* Town seen as vital for rebel advance
* Gaddafi forces still within city
By Rania El Gamal
AJDABIYA, Libya, July 20 (Reuters) - Eighteen rebel fighters were killed and up to 150 wounded in clashes with forces loyal to Muammar Gaddafi for control of the eastern oil hub of Brega on Tuesday, a doctor in a rebel-controlled town said.
“Yesterday it was a disaster,” Dr Sarahat Atta-Alah told Reuters at Ajdabiya hospital in eastern Libya on Wednesday.
Rebels have said they have encircled Brega, which they must take if they are to advance towards Tripoli, but fighters said they were still coming under fire from pro-Gaddafi forces.
Rebels also reported heavy fighting near the western town of Misrata, a longtime insurgent stronghold.
Brega, which provides access to most of Libya’s eastern oil network, has changed hands several times in five months of fighting along Libya’s Mediterranean coast.
Rebels said on Tuesday they had encircled the town, which if captured would mark a major boost for their campaign to oust Gaddafi. Insurgents said they were dug in to the south and east of Brega and in control of its eastern residential sector.
The Libyan government has denied the rebels’ reports, saying its soldiers are in Brega.
Doctors at the hospital in Ajdabiya, which lies to the east of Brega, said they expected more fighting later on Wednesday.
A rebel lieutenant, who gave his name as Ihab, said rebel forces were between 5 and 10 km (3 and 6 miles) outside Brega and Gaddafi’s forces were still in the city.
He said the area was littered with mines and Gaddafi’s forces had filled trenches with gasoline, which could be set on fire if rebels approached.
A rebel soldier named Izzel-Deen said: “Yesterday we saw Brega. We were very close but we turned round when they started shelling us.”
In Misrata, a Reuters team reported heavy fighting on the city’s western front.
Rebel sources said they had to taken two truck-mounted Grad missile positions from pro-Gaddafi forces and captured three wounded government soldiers. One Gaddafi soldier had died, hospital officials said.
In the west, Tunisian residents reported Grad rockets fired by Libyan forces had fallen on Tunisian soil near the Dehiba border crossing. No casualties were reported. (Additional reporting by Nick Carey in Misrata; Writing by Giles Elgood; Editing by Sophie Hares)