Medibank saga 'broken' promise: Shorten

Medibank's refusal to pay hospitals for complications it claims are "highly preventable" amounts to a broken promise from the federal government, Opposition Leader Bill Shorten believes.

The health insurer has warned its near four million members they could face out-of-pocket costs at Calvary hospitals after August 31, when its contract with the hospital operator expires over a dispute.

Mr Shorten says Labor warned of situations like this when the government flagged the sale of Medibank, telling reporters in Perth on Friday: "The government has broken its promise, when it said it would privatise Medibank it said there would be no untoward consequences."