BARCELONA, June 17 (Reuters) - Spanish holding firm Criteria will seek a new partner for a potential takeover bid for utility Naturgy as soon as possible after it recently failed to reach an agreement with Abu Dhabi's TAQA , a Criteria source said on Monday.

Asked if it had to be an industrial partner from the energy sector, the source said Criteria - which owns 26.7% of Naturgy - was open to any shareholder that brings growth to Spain's largest gas company.

The source added that Criteria does not like acting alone when it comes to companies it deems strategic.

When Criteria last week dropped a takevoer plan for Naturgy with TAQA as partner it said it was "exploring new options" to support the Spanish energy company's transformation plan. It also reaffirmed its commitment as a long-term investor in Naturgy.

Criteria, which is the investment arm of La Caixa Foundation, is looking for long-term shareholders and those that agree with its long-term strategy, the source said in a briefing with reporters.

Criteria would likely be open to splitting Naturgy in different units but only if it would bring value, the source added.

TAQA was in takeover talks with Naturgy's three largest shareholders - Criteria and private equity funds CVC and GIP, which each own more than 20%.

Another source with knowledge of the matter said the deal was called off due to disagreements over the price and governance issues without elaborating further.

With Naturgy's planned takeover, TAQA, a power and water utility founded in 2005, would also have acquired the Spanish firm's contracts with Algeria and a long-term contract to import some 3 billion cubic metres of Russian liquefied natural gas every year. (Reporting by Joan Faus and Jesús Aguado; Editing by Aislinn Laing, David Latona and Tomasz Janowski)