* Officer says rebels control desert west of Ajdabiyah
* UK military advisers arrive to help rebels - spokesman
* Rebels seek to prove they can hold territory
(Adds comment from rebel spokesman, detail)
By Michael Georgy and Deepa Babington
AJDABIYAH, Libya, April 26 (Reuters) - The Libyan army has reinforced positions around the eastern oil town of Brega and dug in its long-range missile batteries to conceal them from attacks by NATO warplanes, a rebel army officer said on Tuesday.
Rebels intent on overthrowing Muammar Gaddafi fought battles with government loyalists for weeks after an uprising erupted in February, but fighting has reached stalemate on the desert road between Brega and Ajdabiyah, 80 km (50 miles) further east.
Insurgent fighters reported clashes in Brega last week. Comments by rebel officer Abdul Salam Mohammed suggested Gaddafi now had clear control of the town, which is home to a major oil exporting terminal.
“There are 3,000 government troops in Brega and the next two towns. They have been building up their presence,” he told Reuters on the western edge of Ajdabiyah.
Mohammed said Gaddafi forces had dug tunnels to hide their Grad rockets and stop them being attacked by NATO air strikes.
“We are controlling the area from here to al-Arbeen (halfway to Brega) but they still have snipers in the area, hiding in the desert behind the sand dunes, and they are active,” he added.
Rebel military leaders say they have changed tack after their forces were beaten into a chaotic retreat from near Gaddafi’s home town of Sirte hundreds of kilometres further west in late March.
Many rebel fighters are enthusiastic youngsters with light weapons and little battle experience and the regular rebel army — units that defected from Gaddafi and former career soldiers — has told them to stay back from the front line.
The rebels have erected barricades near the western entrance to Ajdabiyah, the last major town before the main rebel base of Benghazi and the key oil exporting terminal of Tobrouk, suggesting a more concerted effort to defend against any ground assault by Gaddafi’s better equipped troops.
“We are focused on getting our house in order and we are trying to protect the gains we have achieved,” rebel spokesman Jalal el-Galal said in Benghazi.
He said British military advisers had arrived in the city and he hoped the rebel army would soon begin to improve its organisation, and its coordination with NATO forces attacking Gaddafi’s positions.
“You won’t see a result in 24 hours but we are trying to be more efficient,” said Galal. (Writing by Tom Pfeiffer; editing by Giles Elgood)