By Alexander Cornwell

DUBAI, June 22 (Reuters) - Etihad Airways is to open up its lounges to economy class passengers for a fee and will start charging for chauffeur services that had been complimentary as it joins rivals in looking for new ways to boost revenues.

The changes, announced on Thursday, come amid a strategy review at the Abu Dhabi carrier as once rapidly expanding Gulf airlines face tighter profit margins amid overcapacity in the market and tighter corporate travel budgets.

The fee for economy passengers to access the business class lounge at Abu Dhabi International Airport will start from 370 dirhams ($101) and will depend on how much time is spent in the lounge, an Etihad spokesman said. It will also offer economy class passengers paid access to its lounges at other airports around the world.

The changes, effective on July 3, will also allow business class passengers to pay to use the first class lounges, whilst a previously complimentary chauffeur for business and first class passengers will become a paid for service outside of Abu Dhabi.

Etihad will also open up the service to economy passengers.

Will Horton, senior analyst at Australian aviation consultancy CAPA, said chauffer services have always been a high-cost for airlines so to start charging for them was "not surprising."

Passengers travelling in the three-room suite available on Etihad's Airbus A380s, dubbed 'The Residence,' will not be charged.

Rival Emirates said in January it would allow economy class passengers who are frequent flyer members to pay to access its lounges. That followed an earlier decision to introduce fees for advanced seat selection for economy passengers.

Other changes at Etihad include introducing a bidding system for economy passengers to pay to have up to three empty seats next to their own, following similar systems in place at some other airlines.

"Airlines are increasingly asking what they have and do not sell but could," Horton said. "Airlines have been allowing passengers to bid for upgrades but guaranteeing an empty seat next to you is still catching on."

($1 = 3.6723 UAE dirham)

(Reporting by Alexander Cornwell; Editing by Susan Fenton) ((Alexander.Cornwell@thomsonreuters.com;))