Benedict Rogers said he is still awaiting an explanation from authorities over why he was refused entry by border security staff on Wednesday.
He told Premier: "If basic freedoms, the space for civil society and the space for free-thinking in Hong Kong continues to shrink... then, at some point further down the line, that is going to affect the church and affect religious freedom."
The deputy chairman of the Conservative Party's human rights commission, Mr Rogers has been an outspoken critic of Beijing's track record on human rights.
He claims airport staff in Hong Kong took him aside after his arrival on a plane from the Thai capital Bangkok on Wednesday morning.
The case fuels concern that the so-called 'one country, two system' principle - established when the UK handed over control of Hong Kong - is being undermined and China is exercising undue influence.
Mr Rogers said: "The decision to deny me entry was not taken by the Hong Kong authorities. It was taken by the Chinese government and that, therefore, undermines the principal of Hong Kong people running Hong Kong.
"If China has control of Hong Kong's immigration and has the power to deny people entry simply because they've been critical of China's human rights record and the threats to Hong Kong's freedom, then that's a very serious concern."
Earlier this week, the foreign secretary Boris Johnson said the UK will seek an urgent explanation from the Hong Kong authorities and from the Chinese government" over the case.
Premier has contacted the Chinese embassy in London for a response: