The uncle of North Korean leader Kim Jong-un headed to China Monday for talks on the joint development of two special economic zones, the North's state media reported.

Jang Song-thaek is leading a North Korean delegation for a third round of talks on the Rason Economic Trade Zone and the Hwanggumphyong and Wihwado Economic Zone, the Korean Central News Agency reported.

Jang -- the husband of former leader Kim Jong-il's sister Kim Kyong-hui -- is also vice chairman of the North's National Defence Commission, according to the South's Yonhap news agency.

North Korea and China are jointly developing the Hwanggumphyong and Wihwado zone on two islands in the estuary of the Yalu river that marks their border.

Ground was broken in December.

North Korea announced in June that foreigners would be allowed visa-free access to the new economic zone near its west coast, along with tax breaks.

Yonhap said in February that China would invest about $3 billion in developing a free trade zone around the northeast port of Rason bordering China and Russia.

The impoverished communist country is striving to revitalise its economy through foreign investment in its economic zones.

China, the North's main benefactor, has repeatedly urged it to open up the crumbling state-directed economy.

The North's dependence on Beijing has grown as international sanctions over its missile and nuclear programmes restricted access to international credit.