LONDON — The BBC says it has received reports that its world service English shortwave radio frequencies are being jammed in China and condemns what it called efforts to disrupt free access to news and information.

The broadcaster said while it can't attribute the source of the jamming definitively, "the extensive and coordinated efforts are indicative of a well-resourced country such as China."

The jamming of broadcasts in China is being timed to cause "maximum disruption," the BBC's director of global news, Peter Horrocks, said in a statement Monday.

In the past, BBC Persian transmissions in Iran have been affected by jamming. Jamming frequencies was also a tactic used by communist nations to block BBC broadcasts during the Cold War.