A high-profile state television presenter who launched an online tirade against "foreign trash" has sought to temper his words after calls for overseas guests to boycott his show.

In the diatribe by Yang Rui, published on the popular Sina Weibo service, the Chinese equivalent of Twitter, he described a recently expelled journalist as a "foreign bitch" and praised police for "clearing out foreign trash".

The attack by the host of the English language programme Dialogue, which says it seeks to promote cross-cultural debate, was initially viewed by some commentators as an attempt at satire. His programme is shown on CCTV-9, the channel regarded as part of China's soft power drive to present a more humane face to the outside world.

Melissa Chan, the al-Jazeera journalist expelled from China earlier this month, was the target of the "foreign bitch" remarks by Yang. They followed an announcement by Beijing police of a 100-day crackdown on foreigners illegally living or working in the city and controversy over the behaviour of foreigners in China, including a man – said to be British – who was arrested on suspicion of sexually assaulting a Chinese woman.

"Cut off the traffickers, unemployed Americans and Europeans who come to China to take money, and engage in human trafficking and illegal immigration. Identify foreign spies, who find a Chinese girl to live with while collecting intelligence, posing as tourists to get mapping and GPS data for Japan, South Korea, the United States and European countries," Yang wrote.

"We kicked out that foreign bitch and closed al-Jazeera's Beijing bureau. We should shut up and kick out those who demonise China."

Speaking to the Guardian, Yang said the remarks were a spontaneous response to the police crackdown: "The wording, I acknowledge, is very strong and incompatible with my image as host of a professional talk show and I can say for sure I am sorry for hurting those who respect my profession.

"I don't mean I am beating a retreat from the principles that may be implied in the initial posting. The crackdown on illegal foreigners is a must. Ninety-five to 98% are honest people, well educated and abide by our laws … I am only talking about the bad guys."

His post was still online on Monday evening and, despite coming under fire on Weibo, he has not tempered his comments. He said he initially accepted the translation of the term he used as "bitch", but claimed it did not truly reflect his meaning. "It somehow carries an overtone of sexual discrimination," he said.

"I never meant to humiliate any woman. I respect women. In general terms, I feel China is not covered responsibly or fairly."

Yang has previously said he has to remind himself he speaks not just for himself, but for his country.

He said his Sina Weibo account was personal, but the comments were also carried on his microblog feed on the official CCTV website. A CCTV spokeswoman said: "His microblog is a personal account. It does not represent CCTV; it was a very personal post."

Yang said he believed any effect on guest bookings would be temporary. "If these guys refuse to appear, it's a reflection of cowardice," he said.