N Korea adds more special troops, tanks: S Korea

In a two-yearly defence white paper, the ministry said the size of the special forces had risen by 20,000 to 200,000 over the past two years.

But the total size of the North's military remained unchanged at about 1.19 million, the paper said.

It also confirmed the communist state deployed its new battle tank, "Pokpung-ho" ("Storm Tiger"), which reportedly made its debut in 2002.

North Korea claims the Pokpung-ho is comparable or superior to the Russian T-90 developed in the 1990s.

The paper did not say how many of the new tanks the North has deployed for operational use.

The overall number of North Korean tanks rose to some 4,100 as of last month from 3,900 in 2008, the paper said.

But most of the newly added tanks were old-style equipment deployed in the rear, a military intelligence official told a briefing on the policy paper.

Cross-border tensions are high after the North last month shelled a South Korean border island, killing four people including civilians.