John Reid has said Jeremy Corbyn has not appeared "competent" on national security issues in the wake of the Paris terrorist attacks.
The former Labour home secretary told BBC Radio 4's Today programme on Friday: "It doesn't look coherent if, when the leader says something, within the day a shadow cabinet person - and a series of them - have to come out and disagree, contradict, clarify it, say he wasn't saying what he was saying."
Corbyn was forced to insist he would allow police to shoot to kill terrorists were he prime minister and an attack was underway on the streets of Britain. He had initially said "not happy" with the idea.
Reid said: "I think it is sad that the Labour Party in recent days, I don't think their best friend would argue we had been coherent on these issues, it's sad not only from the point of view of the Labour Party but the country, we need a competent coherent opposition."
Asked whether the party would look more coherent if shadow cabinet ministers "shut up" and stopped contradicting Corbyn, the former cabinet minister said while that might be true it would not be "sensible".
"I think we need, particularly on areas of national security and particularly in times of threat to that national security like this, we need an effective and competent Opposition."
He added: "It is now up to the new generation to try and create success. The only observation I would make is that people like Brown and Blair and Blunkett and the rest of us – we didn't have that victory and that success for Labour fall into our lap," he said.
"It was only at the end of 15 years of political argument and the defeat of the Bennites, the Scargillites, the Militant, the other entrants – all of whom, had they won, would have taken us into the political wilderness.
"That precursor to our success was ideological battle, but that is now a matter to be confronted by the new generation of MPs, not by David Blunkett and myself."
Reid's criticism of the state of the party was endorsed by the current shadow Europe minister Pat McFadden.