* The two companies link up in new push for schedule reliability

* Maersk became possible partner after leaving MSC

* Like-minded on declared decarbonisation

FRANKFURT, Jan 17 (Reuters) - Hapag-Lloyd and Maersk have signed an agreement for a new long-term collaboration starting February 2025 with a combined capacity of 3.4 million containers (TEU), the two shipping companies said on Wednesday.

As part of the agreement, called Gemini Cooperation, the two companies have set the ambitious target of delivering schedule reliability of above 90% once the network is fully phased in, they said in a joint statement.

Rolf Habben Jansen, chief executive of Hapag-Lloyd, said his company would benefit from efficiency gains in operations and joint efforts to further accelerate the decarbonisation of the wider industry.

His Maersk counterpart, Vincent Clerc, said the deal will strengthen integrated logistics offerings and make services more reliable.

The shared pool, involving the world's fifth- and second-largest container ship operators respectively, will consist of 290 vessels of which Maersk will deploy 60% and Hapag-Lloyd 40%.

The current arrangement of operational responses to attacks on ships in the Red Sea by Iranian-backed Houthi militants in Yemen is unlikely to have been a factor in the deal, sources familiar with the deal said.

As a consequence of the agreement, Hapag-Lloyd will leave the shipping alliance called THE Alliance at the end of January 2025, which it shares with three merged Japanese lines called Ocean Network Express (ONE), YangMing of Taiwan and South Korean HHM, formerly known as Hyundai Merchant Marine.

Maersk a year ago said it would end its alliance, called 2M, with rival MSC.

Hapag shares were up 2.6% and Maersk shares up 1% shortly after the announcement but Maersk's gains had shrunk to 0.4% and Hapag's reversed to a 2.5% loss around midday.

Hapag-Lloyd will brief the press on further details at 1400 GMT.

Shipping sources believe that the two companies are a good fit as their business strategy emphasises reliability - which has become crucial for customers since the COVID-19 crisis upset supply logistics and drove up freight rates.

For Hapag-Lloyd, one partner rather than three might also just be simpler, they said.

Also, both partners have declared decarbonisation strategies. Maersk is aiming for net-zero operations in 2040 and Hapag-Lloyd in 2045.

(Reporting by Vera Eckert, Writing by Miranda Murray Editing by Madeline Chambers, Matthias Williams and Emelia Sithole-Matarise)