Metro has cancelled talks with the Rail, Tram and Bus Union over a new three-year pay deal and appealed to the industrial umpire to ban Friday's planned public transport strike.

Metro's snap decision on Monday to halt talks follows several days of fruitless negotiation with the union over the terms and conditions of a new enterprise bargaining agreement.

Stray balloons have led Metro Trains to suspend services on the Sunbury line. Credit:Scott Barbour

The company cancelled talks at short notice and has threatened to withdraw its offer to the union unless it agrees by 5pm.

On Monday evening The Government formally told the union that it would bring both parties back to the negotiating table in return for the RTBU suspending its stop work action planned for Friday.