Tony Blair's speech seeking to rally global support for a confrontation with Islamic extremism generated a storm of reaction, most of it negative and much of it focusing on the messenger rather than the message.

The director of the Council for Arab-British Understanding, Chris Doyle, said the former prime minister had been right to underline the importance of the subject in his Bloomberg speech but was sharply critical of the way he went about tackling it.

Doyle said: "Blair is largely right to highlight the issue. Islamic extremism is not on the wane. It is flourishing in many areas of the world. Nobody should be complacent.

"It is his solutions that are very problematic – particularly the idea that people in the Middle East have to choose between dictatorship and Islamic extremism, and in criticising the Muslim Brotherhood he has endorsed the military leadership in Egypt. But the choice the people of the region need is not between dictatorship and extremism but between those systems and pluralist democratic rule. In fact, dictatorships have often been a significant cause of frustration and anger, and a driving force behind the rise of al-Qaida."

Blair found support for his position from a former foreign office minister, Denis MacShane, who said he had warned about the threat of Islamism in 2003 and was nearly sacked for his stand. He compared Wednesday's speech to Winston Churchill's famous 1946 warning about the descent of the iron curtain.

MacShane tweeted: "Just read Blair speech. Ignore headlines. This is Fulton Mark 2. Bien pensant left then refused to challenge Stalinism. Orwell knew better."

Others complained that the speech conflated different strands in political Islam. The Palestinian editor of the Rai al-Youm news website, Abdel Bari Atwan, said: "Blair is implying that extremist Islam is a danger for the whole world. But the target is the Muslim Brotherhood. He is a very good friend of Mr Sisi in Egypt and he does a lot of consultancy work in the region so it's not surprising that he's speaking out. He had spent years as peace envoy but what kind of peace has he achieved? We have to differentiate between radical Islam and moderate Islam. If you criminalise Islamists like the Muslim Brotherhood then you are pushing them into extremism."

Much of the commentary focused on Blair's own credibility on the subject as much as the subject itself, particularly his role in leading Britain into the war in Iraq alongside the former US president George W Bush.

Doyle said: "Before 2003, there wasn't an issue of al-Qaida in Iraq. There is now. Intervention is highly risky and almost always leads to situations where extremists flourish. They profit from instability, civil war and the inability of states to manage their territories."

A columnist for the Saudi-owned al-Hayat daily, Jihad al-Khazen, said: "Blair and George W Bush are as responsible for radical Islam as any of its leaders. The war in Iraq caused the death of almost a million Muslims. It gave a reason for every radical in the Middle East to go to war against the west.

"I don't think Blair will absolve himself of responsibility by making this speech. He talks about how the Middle East matters but he says nothing about Israel's continuing occupation. He is definitely not the right person to be lecturing on this subject – or to be a peace envoy. That's an oxymoron."

Daniel Seidemann, an Israeli lawyer and expert on Jerusalem, where Blair spends some of his year as envoy for the Quartet (the UN, EU, US and Russia), also noted the absence of any mention of the occupation of Palestinian territories, settlements and the prospect of a Palestinian state.

Meanwhile, a columnist on the Israeli newspaper Haaretz, Anshel Pfeffer, tweeted: "The fascinating thing about Blair's speech today is that it could have been a Netanyahu speech, word-for-word, they share the same outlook."