SEOUL (REUTERS) - South Koreans, who lunch religiously between midday and 1 pm, can now get an extra treat through a smartphone app that promises to help singles find their one true love.

In a country with the longest working hours among rich industrialised nations, and where 8 million of its 50 million people are thought to be single, the i-um app, which means "to connect", offers detailed profiles and photographs to help match up busy singles.

Subscribers register and submit photographs and personal information.

Then at exactly 12.30pm local time each day, they receive a message through a stylised "lunchbox" showing the match of the day - and if both parties click "okay", they receive the other's name and phone number.

"At 12.30 pm, the hour and the minute hand make a straight line. That means that both the man and the woman we connect can become one," said company founder Park Hee Eun, who started the business that developed the app in 2011.

"We (also) chose 12.30 p.m. because it is when people are most relaxed so they can just open the lunch box we deliver in a laid-back manner."

The app now has 800,000 subscribers and so far, 56 people have successfully found mates.

"App dating was my last-ditch effort, (I was) grabbing at straws," said Ms Lee Ji sun, a 33-year-old businesswoman who last month married the man she met through the app.