A suspected acid attack on a three-year-old boy is not believed to have a racial motive, detectives have said.

West Mercia Police said they are working to ensure the safety and security of the victim and his family as they recover from their “shocking” ordeal on Saturday at a Home Bargains shop in Worcester.

Officers are due to question three men in their twenties who were arrested in London early on Monday on suspicion of conspiracy to commit grievous bodily harm, and a 39-year-old man from Wolverhampton arrested on Sunday on suspicion of the same offence.

Speaking at West Mercia Police’s headquarters near Worcester, Chief Superintendent Mark Travis said there were believed to be no links between the incident and an English Defence League (EDL) march held nearby on the same afternoon.

Mr Travis said: “I would like to reassure people both nationally and within Worcestershire that instances of this nature are very, very rare.

“I would like to be very, very clear – there is no evidence to suggest that in any way this incident is motivated by race or anything to do with the EDL protest.”

The child injured in the incident was discharged from hospital on Sunday after treatment for burns to his arm and face but the long-term implications of his injuries are as yet unknown.

Officers have urged the media to respect the privacy of the boy and his family and have said they are keeping an open mind about the potentially “complex” motivation behind the attack.

Mr Travis added: “We are in touch with the family – the family are being supported by specialist officers.

“Clearly it’s a difficult time for them – they are coming to terms with something that is quite shocking.”

The senior officer added: “We need to make sure that whilst we work through the investigation, that they are safe, secure and allowed to deal with the issues that they face at the moment.”

Asked what progress was being made in the inquiry, the officer added: “We have had fantastic support from forces around the country, from West Midlands Police, Warwickshire Police and the Metropolitan Police.

“It’s really important that we do this in a considered manner. We want to make sure that we preserve the best evidence and that we consider the views of the victim and the victim’s family.

“We will seek to get all the information we can to understand what has taken place, to make sure we understand what the motivation behind this was.”

Officers have declined to confirm the ethnicity or nationality of the family and have said they will not issue any further information regarding their identities for operational reasons.

Detectives also refused to say whether those arrested were known to the victim’s family.

Mr Travis said officers had taken possession of CCTV footage and believed that the boy was targeted.

The officer told reporters: “We are keeping all of the options open but at the moment we consider it was a deliberate act against the little boy.

“In terms of what the little boy is saying to us at the moment, that’s something that is a complex process and takes a long period of time. So I am not able to talk about what he or his family are saying to us.

“We work very, very hard to make sure that that process is not intrusive and that people with the appropriate training can look after that little boy and make sure that he can help us and we can help him.”

West Midlands Ambulance Service paramedic Nick Carson, who treated the boy, told the BBC the liquid used in the attack was pink and “had quite a strong smell – not a bleach of acidy-type smell”.

The woman with the boy was “concerned but not panicking” and the toddler calmed down quickly once he was treated.

Mr Carson told the BBC: “We had no inkling or any reason to suspect that it was an acid attack – we just thought that maybe he had come into contact with some sort of chemical. To find out afterwards that that was the case, it’s shocking.”