GREENPOINT - Major weekend service disruptions begin on the G line today, much to the frustration of commuters.

Starting today, the Greenpoint Tube, which carries the G train under Newtown Creek, will be closed for 12 weekends so repairs can be done. Stations affected include Greenpoint Avenue, 21st Street and Court Square.

The MTA says the stops will be closed for 12 weekends and five full weeks sometime next year. Shuttle buses are available on Manhattan Avenue to take over the train's route.

In August, the Montague Street Tube, which carries the R train under the East River, will be closed for 14 months. The closures are so crews can repair electrical and infrastructure components damaged when the tunnels flooded during Sandy last year.