North Korea on Saturday took further steps to mend ties with the South, suggesting talks within weeks and reopening an office to encourage cooperation on the fractured peninsula.

The latest offer from Pyongyang followed an apparent easing in tensions, which have soared since the North shelled the South's frontline Yeonpyeong island on November 23, killing four people.

Pyongyang's committee for the peaceful reunification of the fatherland "formally" proposed an "unconditional and early opening" of talks between the two governments.

"The level of the talks and their venue and the date of their opening may be decided under a bilateral agreement," it said.

The committee, the official agency in charge of exchanges between the two, said in its statement that there is "neither conditionality in the North's proposal for dialogue nor need to cast any doubt about its real intention".

"The South Korean authorities should discard any unnecessary misgiving, open their hearts and positively respond to the North's proposal," it said.

South Korea said the offer, which comes after Beijing said it would "support and welcome" any dialogue between the North and South, was more concrete than a call by Pyongyang earlier in the week for "unconditional" talks.

"The government is now analysing the background and intention of this overture," unification ministry spokeswoman Lee Jong-Joo told AFP.

North Korea also proposed an early resumption of talks between the two nations' Red Cross organisations on humanitarian issues and other negotiations aimed at reviving economic exchanges and cross-border tours.

South Korea in May 2010 suspended almost all cross-border economic exchanges, putting the blame on the North for the sinking of a South Korean warship in March, an allegation angrily denied by Pyongyang.

North Korea responded by closing the office in its Kaesong City near the border that was used to facilitate inter-Korean economic cooperation but said Saturday it would now re-open the office as a "measure of good faith".

Talks on a range of issues, including the resumption of tours of the North's scenic Mount Kumgang and a joint industrial asset at Kaesong should be restarted at an early date, it said.

"We also propose that Kaesong be their venues and they take place at the end of January or in the first half of February," the North said.

Professor Kim Yong-Hyun of Dongguk University said Saturday's overture came in response to the demand from China and the United States that inter-Korean relations should be improved before six-party disarmament talks can be resumed.

The North quit the talks, which group the two Koreas, Japan, China, Russia and the US, in 2009 and staged a nuclear test a month later, its second since 2006, in protest at continuing "hostile" US policy toward the communist state.

"In addition, the North is seeking to obtain economic gains through the resumption of inter-Korean economic exchanges and to stabilise a third generation succession scheme," he said.

Kim Jong-Il, 68, who took over from his father, Kim Il-Sung, is known to be accelerating the transfer of power to his own son Jong-Un after suffering a stroke in 2008.

Relations between the two Koreas were stretched to breaking point after the North's shelling in November, which killed four people including two civilians.

But after a difficult year on the Korean peninsula, 2011 started on a more peaceful note.

The North began the year calling for improved relations with Seoul, while South Korean President Lee Myung-Bak Monday also reached out, saying he was open to talks and offering closer economic ties.

Professor Kim Keun-Sik of Kyungnam University said the North's gesture was also aimed at shifting responsibility for continuing tensions to the South ahead of this month's China-US summit.