Passengers on Virgin Australia are set to enjoy greater access to Air New Zealand's Koru lounges, and vice versa, as the airlines launch their full trans-Tasman alliance later this month.

Members of Virgin Australia's The Lounge program will gain entry into Air New Zealand domestic Koru lounges when flying on domestic New Zealand services, and international Koru lounges on trans-Tasman services.

The changes, due to take effect from July 26, are among those detailed in a briefing booklet issued to travel agents by Air New Zealand on the Trans-Tasman alliance and information supplied to Australian Business Traveller by Virgin Australia early last week.

There are, however, a few caveats. Virgin Australia The Lounge members can use Air New Zealand's 'international' lounges only on those trans-Tasman hops, so there's no swanning into a Koru lounge outside of Australia or New Zealand with a flash of your membership card.

And Air New Zealand's 'contract' lounges in Adelaide and Perth won't be available, even if you hold Velocity Gold status.

Membership to Virgin Australia's The Lounge programme is set to jump from August 1, with the annual fee climbing to $420 from the current $369 while the one-off joining fee jumps from $199 to $280 – making the combined first-year hit a hefty $700.