Ottoway told CNBC that China's move was detrimental to diplomatic relations, which had been on an improving trend since a low point in 2012 when the U.K. Prime Minister offended Chinese leaders by meeting with Tibet's spiritual leader, the Dalai Lama.
"Since then we've had a fairly good direction of travel and trajectory (in Anglo-Chinese relations), and I think now is a setback," Ottoway told CNBC on Monday.
"I'm pressing very much the British government over here to be more forthcoming in their response to this development."
Hong Kong is in the grip of violent protests, in what may be the biggest challenge to China's Communist Party since the infamous crackdown of 1989 in Beijing's Tiananmen Square. On Monday, police charged with batons and pepper sprayed thousands of pro-democracy protestors as they tried to encircle Hong Kong government headquarters.
Protestors are demanding free elections for Hong Kong's next leader in 2017, rather than a vote between candidates endorsed by the Communist Party.
Read MoreWhat's on the minds of HK's young protesters