North Korea has called a rare second session of parliament just five months after holding its first meeting under new leader Kim Jong-un as the destitute state has been sending signals it wants to revitalise its broken economy.

The assembly usually meets once a year to adopt the state budget and to exercise its constitutional mandate to approve key appointments and legal amendments.

In reality it is little more than a "rubber stamp" to endorse decisions by the state leadership.

"The Presidium of the DPRK Supreme People's Assembly Monday made public a decision on convening a session of the Supreme People's Assembly," a brief dispatch by the official KCNA news agency said.

"According to the decision, the 6th Session of the 12th SPA is to be held in Pyongyang on September 25."

DPRK is short for the North's official name, the Democratic People's Republic of Korea. The dispatch did not say what was on the agenda for the session.

The parliament last met in April on the day the North unsuccessfully launched a rocket that was seen as a long-range missile test in disguise and its meeting was largely overshadowed by warnings from the international community over the launch, which sank a U.S. food deal.

North Korea's young and untested leader, Kim Jong-un, has been signalling plans to introduce changes to the ways it runs its economy and agriculture, which have not been able to support its 24 million-strong population.

Kim, who took over in December 2011 after his father died, has projected a sharply different image from his reclusive predecessor, but there has been no firm indication of fundamental switch in his policies.

North Korea's broken economy has been squeezed harder by U.N. sanctions adopted in 2006 and 2009 after the state's missile and nuclear tests and have cut off much the money it made from arms sales, a rare source of hard currency.

Drought and widespread flooding this year are believed to have hit farm production, possibly cutting grain output by as much as 13 percent, a South Korean official said this week in a rare grim forecast by Seoul.

The outlook follows a warning by a Danish aid group that said the North could be facing a return to famine which cost the lives of an estimated 1 million people in the 1990s.

North Korea announced new investment laws this year for its special economic zones on the border with China where it is seeking investment from Chinese companies.

Experts said the new regulations fell short of offering secure and attractive incentives.

A visit to Beijing by Kim's uncle, Jang Song-taek, effectively the second in command in the isolated state, was seen as an attempt to win more Chinese investment and to pave the way for Kim's first visit to North Korea's main diplomatic and economic ally.

(Editing by David Chance)