South Korean spy agency tells lawmakers that North Korea has restarted its nuclear reactor

South Korean lawmakers say the country's spy agency has told them that North Korea has restarted a plutonium reactor at its main nuclear facility.

North Korea said in April it would restart the reactor but has not confirmed that it has done so. Recent satellite photos have shown signs that the reactor may be operating.

The offices of two lawmakers, Jung Chung-rae and Cho Won Jin, say the National Intelligence Service presented its assessment to a parliamentary committee on Tuesday without saying how it obtained the information.

Jung's office cited the spy agency as saying North Korea also conducted missile engine tests at a northwestern site in August.

Defense officials say the engine tests don't mean a launch is imminent.

The spy agency declined to confirm the lawmakers' remarks.