SEOUL - North Korean leader Kim Jong-Il has made more public appearances this year than last, in an apparent bid to quell rumours about his health problems, a South Korean government spokesman said Friday.

The number of times he has appeared in public, mostly on 'field guidance' trips has dramatically increased, said Unification Ministry spokesman Chun Hae-Sung.

The 67-year-old Kim has reportedly made 77 such public appearances in the first six months of this year, with the most recent being to watch a performance by a Russian dance troupe earlier this week, the ministry said.

'The number of field guidance trips, counted from North Korean news reports, has increased drastically this year,' Chun said, adding Kim was reported to have made 50 visits in the same period of 2008.

'We suspect that this is because the North is seeking to show to the people and the outside world that Chairman Kim is vehemently carrying out his official duty,' he told journalists.

The North wants to quash rumours about Kim's health problems, which have circulated widely outside the communist state, Chun said.

Kim is believed to have suffered a stroke last August.

Since then, the reclusive state's leader has given up wearing shoes that add to his height and switched to flat dress shoes or even sneakers to increase his comfort, according to Seoul's Yonhap news agency.

In photographs released by North Korean state media on the eve of Pyongyang's second nuclear test on May 25, Kim was sporting a pair of dark-coloured training shoes along with a grey parka, suit pants and dark sunglasses during a reported visit to a site in the country's north.

Kim has ruled the hermit state largely through two of the highest posts he holds - chairman of the National Defence Commission and secretary general of the ruling Workers' Party - since his father Kim Il-Sung died in 1994.

South Korea's intelligence services have been told that Kim has nominated 26-year-old Jong-Un - his youngest son - to succeed him, a South Korean lawmaker briefed by intelligence officials said this month.

International tensions have grown since Pyongyang's long-range rocket launch in early April and its nuclear test in late May, which led to new UN sanctions.

The North has also fired short-range missiles, renounced the truce in force on the Korean peninsula and repeatedly warned of possible war.

Cross-border relations have soured since a conservative government took office in Seoul in February last year with a firmer policy towards the North.