One man has been charged with possession of an offensive weapon and eight others bailed for a range of offences at a mass protest march in support of the jailed anti-Islam figurehead Tommy Robinson.

Five police officers were injured during clashes between protesters and police at the demonstration in central London on Saturday, which observers estimated drew as many as 15,000 people. Protesters hurled bottles, metal barriers and other objects at police, Scotland Yard said.

One 46-year-old man was charged on suspicion of carrying a knuckleduster; a 50-year-old man was released under investigation for explosives offences after being found with a flare; six were arrested and bailed for public order offences; and one was arrested for possession of cannabis and breach of the peace.

The demonstration came about a fortnight after Robinson, whose real name is Stephen Yaxley-Lennon, was jailed for contempt of court for filming a video outside a trial in Leeds. His conviction came weeks after he drew thousands for a “day for freedom” rally at Downing Street, where he called for freedom of speech to criticise Islam.

Robinson’s supporters came from around the UK for Saturday’s march. They included a football supporters’ group mobilised under the banner of the Football Lads Alliance, protesters inspired by the online “alt-right” movement, elements of smaller hard-right groups, as well as what remains of Ukip – which, since Brexit, has sought to reposition itself and regain relevance – and the newer, more extreme, For Britain Movement.

Michael Bradley, an organiser with Unite Against Fascism, described it as a culmination of several months of activity, beginning with mass marches by the Football Lads Alliance last summer. “There has been a general building up because they can see how well the far right has done in Europe and the US, and the Robinson thing has given them a banner to rally around,” Bradley said.

The march was organised by Hel Gower, who oversees Robinson’s website and is said to be his PA, and Kevin Carroll, Robinson’s cousin and with him a co-founder of the English Defence League (EDL), said Nick Ryan of Hope Not Hate. It was a manifestation of the British wing of a growing international movement, he said, pointing to Hope Not Hate research that found only about half of #FreeTommy tweets originated in the UK, while almost a quarter came from the US.

“[Robinson] acts as a focal point, a lightning rod, for the international anti-Muslim movement: he has engaged with notorious ‘counter-jihadists’ such as Pamela Geller in the US for years, his social media rants and vlogs are shared and amplified many times over by an army of online activists.”

The Dutch MP Geert Wilders, who was previously banned from visiting Britain, was among the speakers calling for Robinson’s freedom. He shared a platform with For Britain Movement’s Anne Marie Waters, Gerard Batten of Ukip, and former Breitbart London editor Raheem Kassam. Kassam claimed he had received a text of support from Stephen Bannon, formerly chief strategist to the US president, Donald Trump.

The London protest was one of several in support of Robinson on Saturday. In Northern Ireland, hundreds of protesters marched to Belfast city hall, carrying union jacks and Israeli flags, and chanting “Oh, Tommy Robinson” and “Free Tommy Robinson”. A protest due to be held in Newcastle was cancelled by North-east Frontline Patriots after Northumbria police told them an Ed Sheeran concert at the same time would leave the force overstretched.

In a reflection of the growing international nature of the far-right movement, Robinson’s case was also raised by a protest in Melbourne, Australia. A rally organiser, Ani Yemini, told Australian media: “Tommy resonates with a lot of people. He’s a working class man, he’s like a typical Aussie. They [Australian supporters] feel like what he says is our future here too.”

A Change.org petition on support of Robinson has received more than 600,000 signatures.