Qatar Airways' business class passengers are being invited to upgrade to first class for free on some of its services to the Middle East.

The offer - the latest attempt by the carrier to boost its market share - is valid on services from Heathrow to Abu Dhabi, Bahrain, Dubai, Kuwait and Muscat via its hub in Doha.

While Qatar is hoping to entice new business with the lure of luxury, rival airlines remain unfazed. 

Emirates, which flies direct to Heathrow - Dubai direct, told ABTN it would not respond with a similar offer, but said: "Emirates has online and special fares on a regular basis. For example, there is currently a business class companion fare on offer from £1500."

A spokesman for Oman Air, which flies direct to Muscat, said: "Oman Air is already providing some of the cheapest fares, and flies the only direct service from LHR to Muscat."

The Qatar deal is only available to A-class passengers (the most expensive bracket in business class), with the upgrade booked at the same time as paying for the flight.

Bookings must be made on or before March 31for travel on or before March 31.

Seats are limited and subject to availability. Flight restrictions and blackout periods apply for travel.

The ticket and upgrade are bookable online at Qatar Airways' website or through a travel management company.