FELLOW football supporters held a minute's applause for the two super fans killed in the Malaysia Airlines atrocity.
They had spent thousands of pounds to fly to New Zealand to watch their beloved Newcastle United play a series of pre-season friendlies.
Before the service Mr Sweeney's father Barry said: "This is one of the most amazing scenes I have ever seen.
"He and John I hope are in the sky, watching this. They would be amazed."
Mr Sweeney, a father of seven who cares for his terminally-ill wife Lesley, said: "I loved him to bits. He was a diamond."
Well-wishers gathered to pay their respects to the dead men, many of them leaving bouquets of flowers with a message to the two well-known fans who rarely missed a match.
One left a bottle of Newcastle Brown Ale as a memorial.
Mr Sweeney was overwhelmed by the scale of the turn-out and thanked everyone for coming.
The informal service, which included a poem to the fans, ended with a minute's applause.
Fans from clubs around the country, including Leeds United, Liverpool and Wolverhampton Wanderers, have left tributes alongside the black and white shirts left by the players' entrance.
Shirts from local rivals Sunderland and Middlesbrough also featured strongly.
A fundraising initiative by Sunderland fans has reached £24,500, when the original aim was to get to just £100. The surplus will be split by the Macmillan Cancer Support and the Sir Bobby Robson Foundation.
Liz Luff, of Sir Bobby's cancer-fighting charity, said: "The atmosphere was incredibly emotional. I've not experienced anything like it.
"It is a wonderful way to remember the pair and it has been very special."
Football fans and relatives of the victims pay tribute at St James' Park
Supporter Malcolm Pegg who spoke at the memorial and knew both men said: "I think it was a fitting tribute for an impromptu gathering.
"Hopefully the bodies will be returned to Newcastle and we can pay a more formal tribute to Liam and John."
Before the tribute, Mr Sweeney urged Russian president Vladimir Putin to act to help the bereaved.
"Mr Putin and all the other big boys - please do something about it," he said. "Please get our kids back. It's not their war and they didn't deserve to be there."
He added: "I have tried not to watch a lot of the news because I don't like what I see - nasty people, soldiers.
Barry Sweeney, father of Newcastle United supporter Liam Sweeney, visits the vast floral tributes to his son at St James' Park
"But the people in the village where it happened have been tremendous. "The villagers are traumatised, it's probably something like what happened in Lockerbie.
"How do people cope with it?"