South Korea Thursday announced a major reshuffle to strengthen the military against threats from North Korea, after fierce criticism of its perceived feeble response to last month's artillery attack.

The defence ministry announced promotions for 111 officers -- 75 from the army, 14 from the navy and 22 from the air force.

It said the promotions are part of a reform drive by President Lee Myung-Bak following the sinking of a South Korean warship in March with the loss of 46 lives.

The South blamed the tragedy on a North Korean torpedo, a charge Pyongyang denies.

Calls for reform grew louder after the deadly North Korean attack on a South Korean border island last month, its first shelling of a civilian area since the 1950-53 war.

"With this reshuffle, the military will strive to build strong armed forces that can fight and win and ensure firm combat-readiness," the ministry said in a statement.

A new army commander, General Kim Sang-Ki, took office Thursday after his predecessor General Hwang Eui-Don quit over a controversial property investment.

Tensions remain high after the island bombardment, which killed four people including civilians. Marines on the island fired back at the North's artillery batteries but did not call in air strikes.

New Defence Minister Kim Kwan-Jin, appointed after his predecessor resigned, has vowed to use air power if the North attacks again.

Pyongyang insists Seoul's forces provoked its attack by lobbing shells into Norh Korean waters, during a training exercise near the disputed Yellow Sea border.

The North's leader Kim Jong-Il has inspected a military unit, the state news agency said Thursday without specifying the date of the visit.

Kim was "greatly satisfied" to hear that its members are "keeping themselves highly vigilant against the aggression moves of the US imperialists and their stooges", it said.

Rodong Sinmun, newspaper of the ruling communist party, blamed current tensions on what it called the "policy of confrontation" by the conservative government in Seoul.

President Lee dropped his liberal predecessors' "Sunshine" engagement and aid policy and linked major assistance to nuclear disarmament, a stance which enraged the North.

"The South Korean authorities should roll back their treacherous 'policy towards the north' at once as they bring the dark clouds of nuclear war to hang over the peninsula," Rodong Sinmun said Thursday.