European Union leaders Wednesday voiced "grave concern" at North Korea's missile and nuclear weapons programmes and called on it to scrap a long-range rocket launch scheduled for next month.

European Council President Herman Van Rompuy said he was deeply worried by the North's plan to launch a satellite. The United States and other nations see the launch as a disguised missile test banned by UN resolutions.

"We remain gravely concerned on North Korea's nuclear weapons and missile programmes... we urge North Korea to refrain from any destabilising act," Van Rompuy said after he and European Commission President Jose Manuel Barroso met South Korean President Lee Myung-Bak.

They and dozens of other world leaders visited Seoul for a nuclear security summit Monday and Tuesday, which discussed ways to protect nuclear materials from terrorists.

Numerous leaders including US President Barack Obama called on the North to scrap the launch, intended to mark the 100th anniversary of the birth of founding president Kim Il-Sung.

Van Rompuy urged the impoverished but nuclear-armed state to divert more resources to feed its people instead of developing costly weapons programmes.

"I need to highlight the gravity of North Korea's human rights situations and the problem of hunger and malnutrition... this should be the first priority for North Korea, not missile and nuclear weapons," he said.

He also stressed the "urgent need" to prevent Iran from obtaining nuclear weapons, and urged all nations to take "robust restrictive measures" against Tehran.

Barroso described the North's human rights situation as "simply incredible" and called on it to improve its dire record.

Pyongyang said Tuesday it would go ahead with the test, reiterating its position that the launch is a peaceful scientific project and accusing Obama of a "confrontational mindset".