By Ahmad Ghaddar, Alex Lawler and Olesya Astakhova

LONDON/MOSCOW (Reuters) - OPEC+ is set to proceed with a planned oil output hike from October, as Libyan outages and pledged cuts by some members to compensate for overproduction counter the impact of sluggish demand, six sources from the producer group told Reuters.

Eight OPEC+ members are scheduled to boost output by 180,000 barrels per day in October, as part of a plan to begin unwinding their most recent layer of output cuts of 2.2 million bpd while keeping other cuts in place until end-2025.

A slowdown in demand growth, notably in China, has weighed on oil prices and prompted some analysts to doubt whether the Organization of the Petroleum Exporting Countries and allies, known as OPEC+, will go ahead with the October increase.

But the six OPEC+ sources told Reuters the plan to increase production remains in place as the loss of Libyan output tightens the market and hopes build that the U.S. Federal Reserve will cut interest rates in mid-September.

"There are many uncertainties on demand but there is also the hope that the Fed's interest rate cut will boost economic growth," one of the sources said.

Saudi Arabian Energy Minister Prince Abdulaziz bin Salman has previously said OPEC+ could pause or reverse the production hikes if it decides the market is not strong enough.

OPEC+ does not have any formal talks scheduled until top ministers on a panel called the Joint Ministerial Monitoring Committee meet on Oct. 2. The JMMC can make recommendations to the wider OPEC+ group.

OPEC, the Saudi government communications office and the office of Russian Deputy Prime Minister Alexander Novak didn't immediately respond to requests for comment.

(Reporting by Ahmad Ghaddar, Alex Lawler, Olesya Astakhova, Ahmad Ghaddar and Maha El Dahan, additional reporting by Yousef Saba, editing by Kirsten Donovan)