Watch: 'These are my nieces and today my nephew was born' – double delight for Jacinda Ardern in touching family moment on Parliament's steps

It was double delight for Jacinda Ardern today, as she was joined by her two adorable young nieces after a public address outside Parliament.

The Prime Minister's adorable young nieces joined her and partner Clarke Gayford at Parliament today after the new Government was sworn in. Source: 1 NEWS

As if being sworn in as the country's new Prime Minister wasn't enough, Ms Ardern revealed even more good news when greeting her nieces on the steps of Parliament.

"These are my nieces and my nephew was born today," the new PM gushed, obviously over the moon.

The Labour leader officially becomes the country's leader in a ceremony at Government House in Wellington. Source: 1 NEWS

Although shy, Ms Ardern's nieces were a hit with the crowd, drawing loud applause as they accompanied "Aunty Cinda" to the top of the steps alongside Ms Ardern's partner Clarke Gayford.

There is no rest for the new Prime Minister though, as she is currently attending her first Cabinet meeting since being sworn in.