The Prime Minister says the Emir of Qatar has promised to see justice done for Martin and Jane Weekes, whose triplets died in a fire in Doha nearly three years ago.
The fire at the Villaggio mall killed 19 people, including two-year-old Lillie, Jackson and Willsher Weekes.
The mall's manager and three others have been convicted of involuntary manslaughter, and given the maximum sentence of six years in prison, while a fifth defendant has been jailed for five years.
John Key, who is in Turkey for the Anzac commemorations, met the Emir, Tamim bin Hamad Al Thani, in Istanbul overnight.
He said the Emir told him he had met with the Weekes family after the tragedy, and that he remained utterly committed to making sure those responsible were held to account.