Image copyright Reuters Image caption Prosecutors say defence lawyers broke a court gag order by making the offer public

Prosecutors in the case of the Colorado cinema massacre have said they will not accept a plea offer from the suspect unless they have more information.

In a court filing, they accused defence lawyers for James Holmes of violating a gag order by making the offer public.

Mr Holmes is accused in the July attack that killed 12 and wounded dozens at a midnight film premiere.

On Wednesday, his lawyers said he would be willing to plead guilty in order to avoid the death penalty.

As they rejected the offer, prosecutors had not said whether they would pursue a capital punishment sentence as part of a trial.

An announcement on the death penalty is expected on Monday from George Brauchler, the Arapahoe County district attorney.

Mr Holmes is charged with multiple counts of murder and attempted murder in the 20 July attack, one of the worst mass shootings in US history.

Prosecutors said the defence has repeatedly refused to give them the information they need to evaluate the plea offer, so the offer cannot be considered genuine.

They did not say what information the defence refused to give them, but the case has been marked by arguments about access to Mr Holmes' mental health records.

They added anyone reading news stories about the plea offer would inevitably conclude "the defendant knows that he is guilty, the defence attorneys know that he is guilty, and that both of them know that he was not criminally insane".