Armed with a diplomatic passport that granted her immediate access, the future queen jumped on a plane in late October when the employee, who is also a friend, and his husband were unable to travel to care for their newborns.

"For me, this is about two babies lying alone in a New Delhi hospital," Mette-Marit said in a statement. "I was able to travel and wanted to do what I could."

She did not alert Indian authorities and spent several days with the babies at the Manav Medicare Centre, where staff assumed the wife of Norway's Crown Prince Haakon was a nanny.

While the princess was away, her name continued to appear in the official palace calendar and her absence from a parliamentary dinner was not explained.

A relative of the two fathers eventually took over from Mette-Marit and the fathers received a visa in November, when they brought the babies back to Norway, the palace added.

Surrogacy is a hotly debated issue in Norway and the government discourages Norwegians from paying surrogate parents for children.

Protestant Norway was the second country in the world in 1993 to register same sex partnerships while same sex marriage has been legal since 2009.

The Crown Princess acknowledged the debate and insisted she is not taking a side and only did what a friend had to do.

"Sometimes life presents you with situations with few good solutions.

This was one of those," she said.