US Secretary of State Mike Pompeo said Friday the United States is looking into reports that several top North Korean officials have been purged in the wake of the no-deal February summit between the countries' leaders.

 "We've seen the reporting to which you're referring," Pompeo said during a press conference in Berlin. "We're doing our best to check it out. I don't have anything else to add to that today."

The Chosun Ilbo, a conservative South Korean daily, reported the same day that North Korea had executed Kim Hyok-chol, its special envoy for the US, along with several foreign ministry officials who had been involved in preparations for the second summit between North Korean leader Kim Jong-un and US President Donald Trump in Vietnam.

The report also said Kim Yong-chol, a top aide to the leader and Pompeo's counterpart in negotiations, was sent to a remote province for hard labor.

The Hanoi summit's failure to produce a deal has been viewed as a major humiliation for Kim Jong-un, who traveled there and back by train.

The summit broke down due to differences over the scope of North Korea's denuclearization and sanctions relief from the US.