It has been confirmed that Ireland's under-19 flanker John McCall died from a heart problem.
Post morten confirms John McCall died of cardiac failure
The post mortem was brought forward from Tuesday to Monday and a pathologist confirmed that the teenager died from cardiac failure.
An IRB statement said that the player's death will be remembered by teams at the U19 World Cup tournament in Durban.
"As a mark of respect a minute's silence will be observed before each of the games on Wednesday," it said.
Meanwhile, the Ireland squad will return home from South Africa following the death of the 18-year-old Royal Armagh School pupil.
The decision was reached between the players and management in Durban on Monday morning.
McCall collapsed during Ireland's opening game against New Zealand on Saturday.
''There are no details yet, but it will be a private homecoming,''said IRFU spokesman John Redmond.
The International Rugby Board and the South African Rugby Football Union fully support the decision and will be assisting the Irish management and team in any way during the coming days.
The IRFU senior vice president Barry Keogh flew out to South Africa on Sunday to oversee matters.
The teenager's father Ian also arrived in Durban on Sunday evening and met with manager Michael Cunningham and coach Pat Murray on Monday morning.
Ireland were due to face Japan in the second phase of games on Wednesday.
The 18-year-old McCall is understood to have taken the ball at the tail of a line-out. He drove forward before being tackled around the ankles before laying the ball back to his team-mates.
When play moved on he failed to move, and despite treatment was pronounced dead a few hours later in hospital.
The funeral will be on Sunday at 1400BST.