SEOUL; North Korea has sent around 1,000 workers to South Africa to help build or renovate stadiums hosting the upcoming World Cup football tournament, South Korean media reports said Monday.

The sanctions-hit state has sent the workers ahead of the June opening of the event, in which its own football team will participate, in an apparent attempt to earn much-needed hard currency, the JoongAng Daily newspaper said.

It said the North Koreans are working at four to five stadiums, including Soccer City in Johannesburg, where the opening and closing ceremonies as well as the final will be staged.

"The North's government will likely demand loyalty from those workers and collect their wages to add to their foreign currency reserve," a Seoul government official told the paper.

Yonhap news agency carried a similar report.

"It appears to be related to the efforts North Korea is increasingly making to earn foreign currency," a source told the agency.

The country's economic difficulties have deepened since it went ahead with a second nuclear test last May and triggered tougher UN sanctions, which banned lucrative weapons exports.

A bungled currency revaluation last November is widely reported to have worsened food shortages and fuelled inflation.

The reports did not say how much the South African government, which has set aside 12 billion rand (around 1.6 billion dollars) to prepare 10 World Cup stadiums, is paying the North Koreans.

In Senegal, North Korean workers are helping to build a 160-foot, 22-million dollar "African Renaissance Monument."

Outside Africa the North has up to 30,000 workers in China, Russia and some Middle Eastern countries, according to JoongAng.

North Korea's football team has qualified for the World Cup for the first time since 1966, when it reached the quarter-finals in England. South Korea will also take part in the tournament.