The US ambassador to Ireland has said the memory lives on of six students who died in a balcony collapse while on working holidays last summer.

Kevin O’Malley led tributes to the dead and injured from the Berkeley, California, tragedy on the eve of the first anniversary, as an apple tree was planted in the grounds of the embassy in Ballsbridge, Dublin.

The students were on J1 working visas for the summer and were among 40 people attending a birthday party when the balcony collapsed in the early hours of June 16 2015.

Another seven sustained serious injuries.

The five Irish students who died were all from south Dublin – medical students and friends Lorcan Miller and Eimear Walsh; Olivia Burke, who went to school with Eimear; Niccolai Schuster, who was at the same college as Lorcan and Eimear, and his friend from school Eoghan Culligan.

Irish-American Ashley Donohoe, who lived in California and was a cousin of Olivia’s, also died.

Mr O’Malley said the people of the US extended heartfelt sympathy to the families, friends, and loved ones of the students who lost their lives or were injured.

“As the tree grows strong, we will take comfort in the knowledge that the memory of Ashley, Eimear, Eoghan, Lorcan, Niccolai, and Olivia, will remain with us always,” the ambassador said.

“We also hold in our thoughts and prayers the young people who are still recovering from their injuries; that they may continue to heal with the love and support of family and friends here and in the United States.

“The remarkable resilience they have displayed sends a powerful reminder to the world of the friendship between our people and of our capacity to unite in times of adversity. I hope the outpouring of love and support from the American people in the aftermath of this tragedy has provided some comfort and brought us closer together.”

A memorial plaque has also been placed in the grounds of the American embassy as part of the tribute.

No criminal proceedings will be brought over the balcony collapse.

After a nine-month investigation, Nancy O’Malley, District Attorney in Alameda County, near San Francisco, found there was insufficient evidence for a manslaughter case.

Initial examinations of the remnants of the balcony showed rot had set in to heavy wooden beams.

Lawyers representing families affected by the tragedy said they are continuing to pursue lawsuits over the disaster.