July 3 (Reuters) - An Australian watchdog said on Friday the proposed merger between energy contractors Subsea7 SUBC.OL and Saipem SPMI.MI will proceed to a Phase 2 review, citing concerns that a deal could trim competition in domestic offshore oil and gas projects.

Here are a few details:

• The Australian Competition and Consumer Commission (ACCC) said the acquisition could lessen competition in the supply of certain subsea infrastructure that connects underwater wells and production systems to surface facilities, services it described as critical to Australia's offshore oil and gas sector.

• Subsea7 and Saipem did not immediately respond to a Reuters request for comment.

• "We will conduct further in-depth inquiries during the Phase 2 assessment and seek more information about the likely competitive effects of this proposed merger," ACCC Commissioner Philip Williams said.

• The decision comes just over a week after Brazil's antitrust agency approved the merger without imposing any restrictions.

• The tie-up between the two providers of offshore engineering and installation services had faced opposition from major oil companies operating in Brazil, which raised concerns about the combined company's market power.

• The deal was opposed by Exxon Mobil XOM.N, Brazil's Petrobras PETR3.SA, and TotalEnergies TTEF.PA, fearing a merged firm would be in a strong position to impose additional costs, delay projects and pressure some clients into exclusive long-term contracts.