FILE PHOTO: The logo of Swiss power technology and automation group ABB is seen during the company's annual news conference in Zurich, Switzerland February 28, 2019. REUTERS/Arnd Wiegmann/File Photo

ZURICH (Reuters) - Swiss engineering firm ABB said on Thursday it had upheld international sanctions on North Korea but its machinery may have been sold to the country without its permission, after photos emerged purporting to show ABB robots in a factory.

South Korean-based website NK News highlighted photos published by North Korean state media showing the country’s leader Kim Jong Un visiting a fish processing factory where machines with ABB logos were in operation.

The photos showed robots using special arm attachments to move large objects on the production line.

The supply of industrial machinery to North Korea is prohibited under United Nations sanctions over its nuclear weapons program.

North Korea has called for an end to sanctions that have crippled its economy, although progress has stalled after it fired two suspected missiles into the sea between the Korean peninsula and Japan in October.

ABB said it complied with all applicable trade sanctions.

“That said, we cannot rule out that some of our equipment may have been resold to the DPR of Korea without our knowledge or permission,” an ABB spokesman said.

In 2015 ABB machinery was photographed in a North Korean factory known to make military products.

A U.N. investigation found it had been indirectly acquired by the country without the company’s knowledge.