South Korea's election watchdog lifted a ban using Twitter and other social networking sites for campaigning ahead of key polls later this year.
The National Election Commission's move came after the Constitutional Court last month condemned the ban as unconstitutional as it eliminated "economic and fair" means of campaigning, the Internet and social networking sites.
"Electioneering by the Internet, emails and social networking sites (SNS) are now allowed," the commission said in a statement.
"Those who are allowed to engage in campaigning can use Internet homepages including portal sites and blogs, as well as emails, mobile messengers, Twitter and other SNS," it said.
The decision was seen as a blow to the ruling conservative Grand National Party as young voters, frequent users of the Internet and social networking sites, tend to support opposition candidates.
South Korea will hold parliamentary elections in April and a presidential poll in December.
During a mayoral election in Seoul in October last year, young voters chatting through networking sites encouraged colleagues and friends to go to the polls and cast their ballots en masse. The election was won by an opposition-backed candidate.
Activist groups welcomed the decision.
"The move marks a major step forward in terms of voters' freedom of expression on the Internet," 52 leftist civic groups, including the People's Solidarity for Participatory Democracy, said in a joint statement.
But the Citizens United for Better Society of the conservative bloc said safeguards should be set up in a bid to prevent the spread of slander and false information ahead of this year's major elections.
South Korea is one of the world's most wired countries, boasting a large population of smartphone and high-speed Internet users.
Explore further: World Wide Web turns 25 years old