Sri Lanka has defaulted on its debt for the first time in its history as the country struggles with its worst financial crisis in more than 70 years. It comes after a 30-day grace period to come up with $78m (£63m) of unpaid debt interest payments expired on Wednesday. The governor of the South Asian nation's central bank said the country was now in a "pre-emptive default". Later on Thursday, two of the world's biggest credit rating agencies also said Sri Lanka had defaulted. Defaults happen when governments are unable to meet some or all of their debt payments to creditors.