North Korea has one of the largest armies in the world
North Korea has bought weapons worth $65m (£37m) over the past five years despite severe food shortages, a South Korean lawmaker said.
Kwon Young-Se said the North had spent about $13m a year during South Korea's previous administration.
He was arguing against the South's so-called 'Sunshine' policy of engagement with the North.
Previous administrations sent food aid to the North, which critics say should have been more closely monitored.
Mr Kwon, of South Korea's ruling Grand National Party, said his information came from intelligence sources, although this was not confirmed.
He said the weapons came from China, Russia, Germany, the Slovak Republic and other countries.
North Korea has relied on foreign food aid for years
"The report shows the North has developed its military capacity despite severe food shortages," Mr Kwon told reporters.
He said more caution should be practised when providing aid to the reclusive, impoverished, communist state.
"Didn't North Korea maintain its regime, introduce weapons and strengthen its armed forces while we were divided over controversy over the reckless aid?" Mr Kwon said in a statement.
Critics of aid disbursements have argued that the food sent to Pyongyang was used to feed members of North Korea's military elite.
North Korea has one of the largest armies in the world, and about a quarter of its national income is believed to be spent on the military.
About 1.7 million people make up the armed forces in a country with a population of 23 million. By contrast, South Korea's army comprises 680,000 troops.
But many North Koreans are going hungry.
In July the UN's World Food Programme warned that hunger in North Korea is at its worst since the famine years of the 1990s, with five to six million people in immediate need out of a population of 23 million.
When he came to office earlier this year, South Korean President Lee Myung-bak promised to stop unconditional aid to the North, which responded by cutting off government-level contact.
Correspondents say the North has not asked for food aid from Seoul this year, and has been bitterly critical of the conservative government which came to power in South Korea in February.