|Despite calls for reunification, tensions still remain high on the Korean peninsula [GALLO/GETTY]
South Korea's president has said unification with North Korea has become more likely as people in the North become more aware of the South's affluence.
Lee Myung-bak said on Thursday, during a trip to Malaysia, that residents of the communist nation know the world is changing, but did not elaborate on how their knowledge has expanded, or how soon unification would come.
"Reunification will definitely come," Lee said in a speech marking the liberation of the Korean peninsula from Japanese colonial rule.
"I believe that the time has come to start discussing realistic policies to prepare for that day such as a reunification tax."
Lee's comments come amid a period of heightened tensions on the Korean peninsula after the North shelled a South Korean island close to a disputed maritime border, killing at least four people.
The North has blamed the South for sparking the exchange of artillery fire last month and criticised both Seoul and its US allies for "provocative" military drills.
The two states are still technically at war having only signed a ceasefire in 1953 and since coming to power in 2008, Lee has abandoned the so-called "Sunshine Policy" of his predecessor for a more strident stance.
Lee said on Friday that North Korea's new understanding of circumstances in the outside world is "an important change that no one can stop".
He added that South Korea has a responsibility to ensure that the North's 23 million people enjoy basic rights, and that Seoul should use its economic power to prepare for unification.
One way Lee proposed was a "reunification tax" to help fund the expected $1 trillion it could cost when the two Koreas eventually rejoin.
He also said it was now time to start saving for the massive cost of reuniting with the North, whose economy has been driven close to ruin by central economic planning, heavy military expenditure and years of famine.
North Korea is one of the world's poorest countries, with annual gross national income of about $24bn in 2009 - less than three per cent the size of the South's economy.
The cost of reunification could wreak havoc on South Korea's economy, with a state-funded research agency saying it would raise the tax bill for South Koreans by the equivalent of two percentage points annually for 60 years.
Opinion polls, however, show more than 60 per cent of South Koreans want unification, but they would prefer it happen later rather than sooner because of the cost.