One of the organisers of the storming of Wembley by thousands of ticketless fans has defended the widely criticised breach, as more details emerged about the scale of the security lapse.

Pablo (not his real name), a 24-year-old from the Midlands, was one of the administrators of a Telegram chat group of hundreds of ticketless fans who shared tips about getting into Sunday’s final. Hours before the kickoff those who succeeded advised those still outside on where breaches had been made, he explained.

Speaking to the Guardian he gave details of how he and about 300 fans entered via a disabled entrance in block K, and he claimed others bribed stewards to get in. He estimated that at least 5,000 entered without a ticket.

Related: Ticketless fans storm Wembley for Euro 2020 final – video timeline

Pablo said he decided to join the so-called “Wembley jib” or entering without a ticket, after trying every day last week to get a legitimate ticket.

He said: “I just thought my Dad is 52 and he’s never seen England in a final at Wembley. And it might never happen again in my lifetime. There were 30,000 spare seats, and we didn’t sit in anyone’s seat.”

Pablo set up a Telegram chat of around 200 ticketless fans. He was also the member of separate chat group with 500 members called “the Wembley Jib”, and was aware of another two other groups including one with 800 members.

Watch: Watch England fans clash with police outside Wembley

Pablo drove down from the Midlands with nine ticketless friends in two cars. All but one of them got in to see the game. He took £250 in cash to pay officials but did not need to use it.

Last week images of real tickets were shared on the chat group, which members used to forge in their own names. Pablo and his friends used such fake tickets to get past a first security check at about 5.15pm. He then regularly checked the Telegram chat for updates on where security had been breached.

Members on the chat claim they had got in by bribing stewards for as little as £20. One member said he got in after paying a steward £120. In an audio message on the chat heard by the Guardian, the man explained how the steward had told him to “put the money in my pocket as I’m patting you down”. The man said: “It was probably more than he earned on that shift. Money talks.”

Pablo said: “A lot of stewards seemed more than willing to help. We offered one £200 to let five of us in. At about quarter to seven, we were waiting for the steward’s mate to show up and that’s when we saw a disabled door open so we just ran through.”

“Every time a disabled entrance was opened there must have been 300 people who got in. And it seemed that every 10 minutes one got yanked open. And that doesn’t count the people who bribed stewards or went behind someone in the turnstiles. I would be shocked if there was less than 5,000 got in without a ticket.”

He added: “When we got in everyone was chanting ‘jib, jib, jib’ up the escalators. We found five empty seats. A family came and one of us was sat in their seat, and they seemed a bit moody, but we just moved along one and no one else came.”

In reference to video showing fans attacking ticketless fans who breached security, Pablo said: “We didn’t harm anyone. The people causing the trouble were the ones fighting ticketless fans.”

Asked how Wembley could stop similar breaches Pablo said: “If there were four of five police officers behind each disabled entrance, that would deter people. Stewards aren’t enough to put you off. But Wembley probably won’t be jibbed on that scale again unless we get the World Cup in 2030.”

An FA spokesperson said a full investigation will take place, in collaboration with police. “The security and stewarding numbers for the final exceeded the requirements for the match and were greater than any other previous event at Wembley stadium,” the spokesperson added.

Watch: Police surprised by Euro 2020 final security breach at Wembley