A US monitoring group says that North Korea may be preparing to carry out another nuclear test in the near future, the Voice of America reported. 

The website 38 North, which focuses on North Korean issues and is run by Johns Hopkins University, said Friday that commercial satellite images taken May 5 over the country's nuclear test site show vehicle movement at a command center, where there is often no activity "except during preparations for a test."

South Korean officials have been on alert in the event that North Korea will conduct a fifth nuclear test to coincide with its high-profile political gathering now underway, the first of its kind in 36 years.

North Korea leader Kim Jong Un opened the seventh Workers' Party Congress Friday by hailing the country's January nuclear test and subsequent launch of a satellite into space.

Wearing a dark Western-style suit, Kim delivered his opening speech before more than 3,400 delegates.

Source: MENA