GENEVA (Reuters) - United Nations human rights chief Navi Pillay called on Monday for an international investigation into what she said were decades of serious violations in North Korea.

She voiced regret that there had been no improvement since Kim Jong-un took power a year ago.

Pillay, in a rare statement on North Korea, said: "Because of the enduring gravity of the situation, I believe an in-depth inquiry into one of the worst - but least understood and reported - human rights situations in the world is not only fully justified, but long overdue."

(Reporting by Stephanie Nebehay; Editing by Janet Lawrence)