A South Korean Catholic charity group delivered 100 tons of flour to North Korea on Thursday, following the resumption of South Korea's flour aid to the impoverished North earlier this week, officials said.

Four South Korean trucks carrying 100 tons of flour crossed the heavily fortified border on Thursday morning to deliver the aid to North Korea to help ease the country's chronic food shortages, the officials said.

The trucks will head to the North's border city of Kaesong where the North Korean authorities receive the aid before distributing it to a hospital and a nursery near Pyongyang, said Shin Hye-young, an official of Caritas Korea.

The Catholic aid agency plans to send monitors to the North in coming weeks to ensure the aid reaches its intended beneficiaries, Shin said before crossing the border, without elaborating.

There have been widespread allegations that the North could divert outside food aid to its elite and military, a key backbone of North Korean leader Kim Jong-il's rule.

The second aid shipment in as many days comes amid concerns that the food situation in North Korea may get worse after recent heavy rains submerged or washed away tens of thousands of hectares of farmland.

The North has relied on foreign handouts since the late 1990s when it suffered a massive famine that was estimated to have killed 2 million people.

On Tuesday, local private groups delivered 300 tons of flour to the North for the first time since the North's deadly shelling of a front-line South Korean island last year.

South Korea slapped sanctions on the North last year in retaliation for the November attack and the March sinking of a South Korean warship.

The attacks worsened public opinion on giving aid to the North, though South Korea has selectively approved humanitarian and medical assistance to its impoverished northern neighbor.

Meanwhile, South Korea has denied another private aid agency's request to travel to Kaesong over its alleged criticism on the government's sanctions on the North.

The aid agency had planned to meet with North Korean officials on Thursday to work out details of aid.

Under the current law, South Koreans are required to get the government's endorsement before meeting with North Koreans and giving aid to the North. (Yonhap News)