North Korea has launched an artillery barrage against a South Korean island, killing two soldier and seriously injuring civilians and troops, in a dangerous escalation of tensions on the Korean peninsula.

South Korea returned artillery fire after North Korea on Tuesday unleashed a hail of 200 shells. Seoul also scrambled F-16 fighter jets and lifted the state of military readiness to its highest level short of war. The government convened an emergency meeting in the war bunker of the presidential office.

The attack, which comes days after North Korea revealed the existence of a previously secret uranium nuclear programme, raises the stakes in an increasingly tense stand-off between the two Koreas by targeting civilians, something Seoul had dreaded could follow the sinking of a warship in March with the loss of 46 sailors.