Adds details on easyJet founder in paragraph 8, analyst comment in 11, details on executives in 15-16, details throughout

By Yamini Kalia

June 22 (Reuters) - Castlelake made public its £4.74 billion ($6.26 billion) takeover plan for easyJet EZJ.L on Monday, ramping up pressure on the board of the budget airline, which promptly rejected it as "opportunistic" and not in its shareholders' best interests.

Minneapolis-based Castlelake, which is a major aviation investor and manages about $38 billion in assets, said the move would allow easyJet shareholders to weigh the bid's merits and relay their views before a June 26 offer deadline.

"There will be increased pressure on the board this week," Goodbody Stockbrokers analyst Dudley Shanley said of the bid price of £6.25 per share from Castlelake made on June 20.

Castlelake said it was the third proposal it had made, disclosing that two previous bids of £5.6 and £6.0 per share put forward on June 12 and June 17 respectively, had been rejected.

Shares in easyJet, founded by British‑Cypriot entrepreneur Stelios Haji‑Ioannou in 1995, rose as much as 5.3% by 1030 GMT on Monday to £5.30, their highest level in nearly a year.

The shares have risen by 27% since Castlelake disclosed on May 29 that it was considering a possible bid for the carrier. Castlelake's latest proposal represents a roughly 57% premium to easyJet's share price on May 29.

VALUATION AND INVESTOR CHALLENGES

"The Board believes that the Third Proposal represents an opportunistic attempt to acquire easyJet 'on the cheap,'" the carrier said in a statement on Monday.

It said it was focusing on its medium-term targets and growing its successful holidays business, as it contends with the impact of the Iran war and weaker bookings.

The airline adds to a growing roster of London-listed firms that have attracted foreign bidders due to the London stock exchange's relatively low valuations compared to U.S. and other stock markets.

Founder Haji-Ioannou, who left easyJet's board in 2010 but is still the biggest investor with a roughly 15% stake alongside his family, declined to comment. He has had a history of public clashes with management over growth plans.

Castlelake said easyJet's "unwillingness to engage meaningfully" was a reason for going public with the bid, which included a partial equity alternative for easyJet investors.

Shanley said the equity offer might be aimed at Haji-Ioannou and his family.

Castlelake said its bid is expected to be fully funded through committed equity and debt, with Goldman Sachs indicating confidence in arranging the required funds.

EU OWNERSHIP REQUIREMENTS

To maintain an EU operating licence, European carriers must under EU rules be majority EU-owned and controlled.

Castlelake said its proposal is backed by former Malaysia Airlines CEO Peter Bellew and senior industry executive Mark Breen, both EU nationals, as it seeks to be in accordance with those rules.

The partnership would bring Bellew back to easyJet, where he served as chief operating officer from 2020 to 2022. He had left Ryanair RYA.I to join easyJet, which prompted a non‑compete challenge that subsequently failed.

Breen is currently CEO of Dublin-based Oneiros Aerospace, having previously worked for Oman Air.

EasyJet said the bidding vehicle is proposed to be owned 49% by Castlelake, and 51% by EU nationals and potentially other undisclosed investors.

Bellew did not respond to requests for comment, while Breen directed queries to Castlelake.

'OPAQUE' OWNERSHIP STRUCTURE

Castlelake said its proposed easyJet ownership structure aligns with models used by other European airlines for compliance, but easyJet argued that the envisaged structure was "opaque" and would not form any basis for assessing the bid.

Shanley said that easyJet equity investors could be disappointed due to the lack of a European airline partner.

Air France‑KLM AIRF.PA and British Airways-owner IAG ICAG.L have long been seen as potential bidders for easyJet, but a takeover would be challenging under current EU competition rules.

While Air France's CEO said two weeks ago that the airline may consider a deal if approached, it is not part of Monday's bid.

($1 = £0.7572)