The brother of the Manchester Arena bomber attempted to buy a bomb-making ingredient but was thwarted by his friend’s father, a court has heard.

Hashem Abedi, 22, is accused of helping to plan the May 2017 attack and to build the suicide bomb that his brother, Salman Abedi, detonated at the end of a concert by the singer Ariana Grande. He denies the murder of 22 men, women and children aged between eight and 51. He also denies attempted murder and conspiring with his brother to cause explosions.

Over the course of two months in 2017 the Abedi brothers allegedly duped friends and relatives into buying the chemicals they needed to make their bomb. But they failed in one attempt to source sulphuric acid after a friend’s father became suspicious and warned his son that the Abedi brothers might have been sourcing the chemical to make explosives, the Old Bailey heard.

At the beginning of March 2017, Hashem Abedi tried to get hold of the friend on repeated occasions, Duncan Penny QC, prosecuting, said. The friend initially agreed to buy five litres of sulphuric acid – one of three components of the explosive TATP – on Amazon for Abedi, the court heard.

Facebook Twitter Pinterest Court sketch of Hashem Abedi in the dock at the Old Bailey. Photograph: Elizabeth Cook/PA

Abedi then asked the same friend to buy some more acid, saying he needed it for a generator battery in Libya to replace some that had been spilled by his brother, jurors were told. He told his friend, who cannot be identified for legal reasons, that he was “skint” so could not buy it himself, Penny said.

However, an order for £76 worth of acid was declined because of a lack of funds, prompting the friend to speak to his father to try to borrow the money, the court heard. But the father refused to help, saying that the chemical could be used to make explosives, it was alleged.

Penny said: “His father said no and explained that acid could be used to manufacture explosives, and so no purchase was ever completed. He ignored further calls which were made to him by the defendant over the coming days.”

Days later, Abedi was in contact with other friends and acquaintances, making multiple transactions and depositing money in their bank accounts, money that was subsequently used to make purchases of sulphuric acid on Amazon, the court heard.

The prosecutor, examining phone records of various associates, told jurors that sim cards were regularly swapped between smartphones and phones not connected to the internet, sometimes staying in a handset for just a few moments.

The prosecution alleges that Abedi helped his brother in his efforts to stockpile chemicals and materials to make the bomb, making him “just as guilty”.

At about midday on Wednesday, part-way through the evidence, the trial had to be halted after the defendant complained that he was “in some pain”. The court heard that Abedi had been feeling unwell before proceedings started but decided to attend nonetheless.

The judge, Mr Justice Jeremy Baker, told the jury that Abedi was “feeling worse not better now and is in some pain”. Baker said it would be inappropriate to continue in the absence of Abedi and adjourned the hearing until the following day.

“It is important that Mr Abedi is able to concentrate on the opening and for that reason I have arranged for some inquiries to be made about his condition, to ensure that if he needs any medical intervention it is provided properly and effectively,” he said.

The trial continues.