Police have condemned “speculation and ill-informed comments” on social media about violence that erupted during a Tommy Robinson campaign rally in Oldham.

Greater Manchester police said bricks and eggs were thrown during clashes between supporters of the anti-Islam activist, whose real name is Stephen Yaxley-Lennon, and counter-protesters on Saturday night.

Ch Supt Neil Evans said on Sunday that those responsible for the “disgusting” acts of violence would be brought to justice after two police vehicles were damaged in the disturbance.

He criticised the circulation of “unhelpful” speculation about the disorder. The force has denied reports that someone was stabbed as well as rumours of a shooting – claims that were still being promoted on Sunday by Robinson’s supporters.

Evans said: “Today, I know people are still feeling the effects of the disturbance that happened yesterday evening and there’s a lot of speculation and ill-informed comments on social media. When any type of event escalates in this way, it’s extremely frightening and upsetting for people in the local area and for the majority who act in a respectable manner.

“For the small few who ruin this for everyone else, let me be clear: you can expect to be identified, investigated by us and brought in for questioning.”

A live video posted on Facebook – but apparently since deleted – by a group calling itself the Muslim Defence League showed a group of Asian men standing and shouting at another group across the police blockade, with some appearing to throw objects and shouting “racist scum”.

A separate live video shared on YouTube by Robinson’s campaign organiser, Danny Thomas, appeared to show the clashes from the other perspective. In the clip, he claims bricks are being thrown at his group.

The violence erupted when Robinson was due to make an appearance in the Oldham neighbourhood of Limeside as part of his campaign for the European elections, in which he is standing as a candidate for North West England.

On Sunday, he is expected to visit the Bootle and Huyton areas of Merseyside. Voting in the election takes place in the UK on Thursday, with counting to start next Sunday.

Evans said: “Since last night, we’ve been working alongside our partners and people in the community and will continue to do so over the coming days. I understand that people will still have concerns around this and while our investigation continues, officers will be patrolling the area so feel free to approach them with any concerns you may have.

“Speculation around what happened is proving unhelpful, but if you do have footage or images that could help our investigation, please send them directly to us.

“No one deserves this sort of thing to be happening in their hometown and I’m determined to – with the support of our partners and you, the people of Oldham – bring those responsible to justice.”

Jim McMahon, the Labour MP for Oldham West and Royton, tweeted about the violence. The shadow local government minister wrote: “It’s horrible to see our town being used for hate and division when our own future is a shared one, long after the circus has left town.”