A spokesman for Anders Holch Povlsen, a Danish billionaire and Scotland’s largest private landowner, told multiple news outlets the siblings were among the 290 people known to have died in a string of explosions.
The spokesman said: “Unfortunately, we can confirm the reports. We ask you to respect the privacy of the family and we therefore have no further comments.”
The names of his children have not been released, but they were reported to have been visiting Sri Lanka over the Easter break.
Several UK media outlets are reporting that a British mother and son eating breakfast at the Shangri-La hotel also died in one of the attacks, alongside five Indian guests.
The overall death toll now stands at 290 people, with almost 500 wounded.
Who is Anders Holch Povlsen?
Povlsen is reported to be Denmark’s richest man.
His fortune comes from his ownership of the Danish fashion group Bestseller, which is the largest stakeholder in the online giant Asos, with 26.66% of the company.
Bestseller also owns more than a dozen brands including Jack & Jones and Vero Moda.
Povlsen is known to love Scotland and be passionate about rewilding. He began buying up Scottish estates in 2006.
The Sunday Times has reported that he is now the largest individual private landowner in Britain, after he spent around £70m ($90.9m) acquiring land over a decade.
Denmark’s foreign ministry said on Monday three Danes had been killed in the bombings.
What do we know about the attacks so far?
Five Britons have been been confirmed dead, but the vast majority of the victims are Sri Lankan.
Warnings have been issued about possible further attacks in the capital, Colombo, or elsewhere on the island in the Indian Ocean, which had seen its popularity soar as a tourist destination in recent years.
The Sri Lankan government has said it will use emergency powers to find suspects and prevent further explosions. The bombings have been blamed on militants with foreign links.
No group has so far claimed responsibility for the blasts on Easter Sunday on two churches and four hotels around the capital, Colombo.
The country only emerged from decades of civil war 10 years ago, when the government won its long battle against separatists from the Tamil ethnic minority.