Andrew O'Donnell and Max Wall, both 18 and former pupils at St Michael's College, died over the weekend as they celebrated the end of their Leaving Certificate exams.

Today, hundreds of young Irish students formed a guard of honour as vehicles carrying their bodies departed the island for Athens.

Around 90 St Michael's pupils were on Ios to celebrate the end of the Leaving Certificate, a rite of passage for Irish teenagers.

Up to a thousand Irish students from different schools are believed to be holidaying on the island.

Andrew went missing after a night out on Friday, and his body was found on Sunday morning in a rocky field, with signs of a fall.

Max was found unresponsive near the port area in a separate incident later on Sunday.

It is believed he may have died of natural causes, and currently it is not believed the two tragic incidents are connected.

There is no suggestion of any foul play in either of the deaths.

Greek police are conducting two investigations, and the Irish police service An Garda Siochana told Sky News two of its officers travelled to Ios "to provide assistance with the ongoing investigations and with the repatriation of both men".

"As this is an investigation led by Greek authorities, An Garda Siochana has no further comment at this time," a spokesperson added.

The parents of both teenagers have also travelled to Ios.

'Max and Andrew died among their friends'

Students and parents filed past a pile of floral tributes at the gates of St Michael's as they attended a prayer service at the school.

The chaplain, Fr Paddy Moran, told those gathered that "Max and Andrew died among their friends", and they should "hold onto the hope that Christ gives you".

Services were held today and tomorrow in memory of the two students, and a memorial will be held later in the week.

Books of condolence have been opened at the school, which has said in a statement that Max was "a constant source of positivity" and described Andrew as a "popular" student and a "committed" footballer.

Meanwhile, friends of the dead students put their grief behind them today to help Ireland's U20 rugby team advance to the World Championship semi-finals in South Africa.

Six former St Michael's pupils, who knew the deceased pair, are part of the squad and were said by their coach Richie Murphy to be shocked and devastated.

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Paragliding accident results in death

That grief was compounded yesterday by the sudden death of the father of another team member in a paragliding accident near Cape Town.

Greig Oliver, a former Scottish rugby international, was in South Africa to support his son, U20 squad member Jack Oliver.

The 58-year-old was killed after two tandem paragliders collided.

Despite the triple tragedy, the Irish team, wearing black armbands, overcame Fiji 47-27 to top their group and qualify for the semi-finals in an extremely emotional atmosphere.

Before the game, captain Diarmuid Mangan said: "A lot of lads in our squad would have known the two boys. Everyone is just kind of trying to get around the lads and make sure they're doing all right and they're being picked up.

"It's obviously an awful tragedy and we offer our condolences to the two families."

A post-mortem examination of both young men is expected to be concluded in Athens by Wednesday.