Tony Blair has defended the Egyptian army's decision to remove Egypt's first elected leader - amid violent protests which have claimed more than 30 lives.
The former prime minister - now the Middle East peace envoy for the US, Russia, the EU and the United Nations - said the alternative would have been "chaos".
Supporters of ousted Islamist president Mohammed Morsi have vowed to fight until he is restored with little sign a peaceful resolution is on the cards.
Blair said while he supported democracy, "efficacy is the challenge" and the Morsi administration had patently failed to deliver in its first year.
While 17 million people on the streets opposing the regime did not constitute an election, such an "awesome manifestation of power" would prompt the fall of a British government, albeit without military intervention, he said.
The world must "engage" with the interim government to help it deliver badly-needed economic reforms because "we can't afford for Egypt to collapse", he warned in an article for The Observer.
And he said one positive to be emerging was that there was "open debate about the role of religion in politics" and "probably a majority for an intrinsically secular approach to government in the region".
"The events that led to the Egyptian army's removal of President Mohammed Morsi confronted the military with a simple choice: intervention or chaos," he wrote.
"Seventeen million people on the streets are not the same as an election. But it as an awesome manifestation of power.
"The equivalent turnout in Britain would be around 13 million people.
"Just think about it for a moment. The army wouldn't intervene here, it is true. But the government wouldn't survive either."
He added: "I am a strong supporter of democracy. But democratic government doesn't on its own mean effective government.
"Today efficacy is the challenge.
"This is a sort of free democratic spirit that operates outside the convention of democracy that elections decide the government.," he said - noting that it was fuelled by social media.
"It is not always consistent or rational. A protest is not a policy, or a placard a programme for government. But if governments don't have a clear argument with which to rebut the protest, they're in trouble."
Morsi's Muslim Brotherhood administration "was unable to shift from being an opposition movement to being a government", he argued, presiding over a "tanking economy", an absence of ordinary law and order and failing services.
An "excellent" tourist minister quit over the president's "mind-boggling" appointment of someone linked to a group responsible a terror attack which killed 60 tourists in Luxor 1997 as its governor.
Blair said we "must hope" further bloodshed could be avoided but the new rulers will have to take "some very tough, even unpopular decisions".
He cautioned that young people had too much faith that democracy itself was the solution and that some he met in the wake of the revolution which toppled the previous president Hosni Mubarak had economic ideas "well to the old left of anything that had a chance of working".
Blair was criticised by Tory former foreign secretary Douglas Hurd.
"Tony Blair leaps in before he's thought things through. We know that already and he's done it again on this," he told BBC1's Andrew Marr Show.
"The seizure of power by the military was the second act in a drama that is going to go on and on and on.
"We won't know for weeks, maybe even months, whether the military...have made a good gamble for Egypt or bad."
"We need to keep our heads and not rush to judgment. Tony Blair is someone who rushes to judgment."
Leaders in Britain and elsewhere had to "grit your teeth" and work with whoever is in power, he said.
"We should not go out of our way to clap our hands and say 'that's marvellous' as Tony Blair has done. We should keep our counsel, keep our wits about us, and wait for the last act of the drama which may be some years away."