South Korea's ruling party chief has drawn political fire and online ridicule after he posed with what he said were North Korean artillery shells but turned out to be charred thermos flasks.

Ahn Sang-Soo, chairman of the conservative Grand National Party, held up the two cylindrical objects before cameras in a bombed-out house on the frontline island of Yeonpyeong the day after it was attacked by the North.

The artillery and rocket strike on November 23 - the first by the North on a civilian area in the South since the 1950-53 war - left four people dead and 18 others wounded, triggering outrage in Seoul and around the world.

TV footage on the day showed Mr Ahn, dressed in military camouflage, saying: "These are shells. They must have landed right here".

One camera then zoomed in on one of the bottles, revealing a trademark logo indicating the objects were metallic vacuum flasks.

Mr Anh has since been targeted by a barrage of political attacks and online sniping over his alleged ignorance of military matters, despite his tough rhetoric in calling for a military build-up against Pyongyang.

Mr Ahn in his defence said he was handed the objects by a guide who had identified them as shells, but that has not stopped the ridicule.

The main opposition Democratic Party's spokeswoman Cha Young said: "We hope that Chairman Ahn bears in mind that he is not a comedian but the head of the ruling party who should ease the people's anxieties about security."

- AFP