North Korea has held a photo exhibition and a youth art festival to celebrate the upcoming 112th birthday of late founder Kim Il-sung, state media reported Tuesday.

Kim died of heart failure in 1994 at age 82, opening the way for his son, Kim Jong-il, to take over in communism's first hereditary succession of power.

Despite the senior Kim's death, his birthday, April 15, is revered as the Day of Sun and is celebrated as one of the communist country's most important national holidays along with his late son's birthday in February.

The North opened the photo exhibition Monday in Pyongyang with photos and videos featuring the two late leaders and their grandson and current leader Kim Jong-un, according to the Korean Central News Agency.

In a separate dispatch, the KCNA said about 1,200 participants held performances in a youth art festival that began Monday in an apparent move to drum up a festive mood for the anniversary of Kim Il-sung's birthday.

The festival comes amid lingering tensions over a series of missile launches by North Korea in recent months in violation of UN Security Council resolutions.

Syrian President Bashar al-Assad, meanwhile, sent a congratulatory message to the North's leader Kim Jong-un over his grandfather's birthday on Sunday, expressing hope for stronger ties between the two nations.

Seoul's unification ministry said what's unusual is that North Korean state media has been referring to Kim's birthday as "a holiday in April" or "a spring holiday in April" in recent weeks instead of the Day of Sun.

"I think it will be appropriate to assess (what that means) after comprehensively looking at April 15-related reports," a ministry official told reporters, when asked if North Korea is viewing Kim's birthday as less important than before.

This year, North Korea is not likely to hold a large-scale military parade to mark Kim's birthday, as the country has usually held such a military event on anniversaries whose final numbers end in a five or zero.

The South Korean military is closely monitoring Pyongyang's possible preparations for provocations on the occasion of Kim's birthday and the founding anniversary of the Korean People's Revolutionary Army on April 25. (Yonhap)