After North Korea's leader Kim Jong-un ordered his army to be prepared for war with South Korea following an exchange of fire along the border on Thursday, concerns of an all-out conflict gripped Twitterati, who expressed their fears through the Twitter trend #PrayForKorea.

Kim Jong-un put his troops in a 'quasi-state of war', after South Korea responded to a border shelling by firing dozens of shells at North Korea.

The North Korean leader threatened South Korea with military action if it continues its loudspeaker propaganda campaign along the border, warning it to take down the speakers within 48 hours from Thursday.

"Commanders of the Korean People's Army were hastily dispatched to the front-line troops to command military operations to destroy psychological warfare tools if the enemy does not stop the propaganda broadcast within 48 hours and prepare against the enemy's possible counteractions," North's Korean Central Television reportedly said, according to South Korea's news agency Yonhap.

South Korean President Park Geun-hye also ordered the military to retaliate if North Korea made any provocations, Yonhap reported.

Twitterati the world over reacted to the news of flaring military tension between the two Koreas, which have remained in a state of war since 1953. #PrayForKorea became a worldwide trend on Twitter, getting tens of thousands of mentions on Friday. 

Many of those who tweeted were presumably South Koreans, as North Korea has blocked access to all social media.

Here are some tweets under the #PrayForKorea hashtag -