A man has claimed he was forced to squirt acid on a three-year-old boy after being threatened with a gun, telling a jury he felt terrible when he found out the child had been burned.

The child, who cannot be identified for legal reasons, sustained serious injuries to his face and arm at the Home Bargains store in Worcester on 21 July last year.

Adam Cech, 27, from Birmingham, is one of seven people, including the boy’s father, who deny the charges relating to the attack.

Cech, who accepted that he did splash the boy, told the jury at Worcester crown court on Wednesday that he did not know the bottle contained acid, and that he discovered the fact only when he saw reports on the news later that day.

The boy’s father, aged 40, has denied a charge of conspiring to spray sulphuric acid on the boy with intent to harm. He is on trial accused of plotting the attack alongside Cech, four other men and a woman.

Cech claimed another of the co-accused, Norbert Pulko, forced a bottle into his hand after threatening him with a gun moments before the attack. When asked by his barrister, Andrew Copeland, how he felt on hearing he had burned the child, Cech replied: “Terrible.”

He claimed Pulko had been driving him to London when he came across a news report of the attack: “I asked him: ‘What was in that bottle, how was it possible that I have harmed this boy?’”

Cech has pleaded not guilty to being part of the conspiracy, alongside the co-accused Jan Dudi, 25, also of Birmingham, and Pulko, 22, of London. Martina Badiova, 22, of Handsworth, Birmingham, Jabar Paktia, 42, of Wolverhampton, and Saied Hussini, 42, of London, have also denied the same charge.

Jurors had previously heard that the child repeatedly screamed: “I hurt” after being sprayed.

The crown has alleged the father enlisted others to attack the boy to try to win a custody battle by discrediting his estranged wife. The jury have seen a BB gun, found by police in Pulko’s bedroom, which Cech claimed was the one used to threaten him into carrying out the attack. After his arrest, Cech gave a “no comment” interview to police.

When asked by Copeland why he hadn’t told police his account at the time, Cech replied: “I was scared, frightened, and it was the first time I’ve ever been in a police station.”

The trial continues.