* Ryanair could deploy 20 planes in Italy at short notice
* Deployment could rise to 30 planes
* Several rivals have declared interest in routes, not Alitalia (Adds quotes, background)
By Julia Fioretti
BRUSSELS, May 23 (Reuters) - Irish airline Ryanair is ready to deploy up to 30 planes in Italy to replace capacity lost if Alitalia collapses or is restructured but does not want to buy the struggling Italian carrier, Chief Executive Michael O'Leary said on Tuesday.
Ryanair's view mirrors the stance of rival easyJet and British Airways owner International Airlines Group (IAG), which have both said they are interested in replacing Alitalia capacity but say they do not want to buy the airline.
Alitalia has filed for bankruptcy protection and a commissioner was appointed to review its future and determine whether it can continue under a new business model.
The commissioner, Luigi Gubitosi, has said that Alitalia's long-haul traffic is doing well and that selling the airline in one block would be the preferred option.
Asked at a Brussels news conference whether Ryanair would be interested in buying Alitalia, O'Leary replied with an unequivocal "no", adding that his company had submitted an expression of interest only because it wants to "participate in the process".
Ryanair is instead preparing to deploy up to 20 aircraft initially over a two-week period this summer if Alitalia cuts capacity significantly.
"We've written to the Italian government and we've said 'look, if something untoward happens, don't worry, we will step into the breach'," O'Leary said.
The planes will be found by tweaking schedules and extending leases, he said, adding that the potential deployment could increase up to 30 planes over the next 12 months.
Ryanair might take "a couple of additional deliveries" from Boeing over the next 18 months, he said.
Last week easyJet Chief Executive Carolyn McCall said that she had no interest in buying Alitalia, adding to rejections from the heads of IAG, Lufthansa, Air France-KLM and Norwegian Air Shuttle.
Any short-haul capacity cut by Alitalia would lead to "opportunities for easyJet," she told analysts after the airline reported first-half results, adding that Rome and northern Italy would be of particular interest.
Willie Walsh, head of IAG - which also owns Iberia, Vueling and Aer Lingus - said this month that the group's airlines, in particular Vueling, could speed its growth in Italy, depending on what happened with Alitalia.
Italy is one of Europe's largest travel markets and a big tourist destination, but short-haul routes are dominated by low-cost carriers such as Ryanair and easyJet.
Ryanair now has a 28 percent share of capacity from Italy to western Europe, against 12 percent for easyJet.
Writing by Conor Humphries and Victoria Bryan; Editing by Susan Thomas and David Goodman