Boeing Co. is preparing to split control of a factory complex in Belfast, Ireland with arch-rival Airbus SE as Spirit AeroSystems Holdings Inc. struggles to line up a third-party buyer for some of the assets.

Boeing ( NYSE: BA) is set to take control of part of Spirit AeroSystems' ( NYSE: SPR) operations in Belfast, Ireland, alongside rival Airbus ( OTCPK:EADSF) ( OTCPK:EADSY ), as efforts to find an independent buyer for the site have so far fallen short.

Britain's competition regulator is considering whether Boeing's deal to acquire its former subsidiary Spirit AeroSystems could affect competition in the country or in other markets, it said on Thursday.