Mo Shaoping says the German Embassy invited him to a Thursday evening dinner. That was to be followed by a private meeting with Merkel to discuss China’s legal environment and individual lawyers who have suffered from official harassment.

However, Mo said Friday that state security bureau agents from the Beijing police arrived at his office at about 2 p.m. Thursday and told him he could not attend, citing the need to maintain social stability ahead of this fall’s Communist Party congress.

There was no immediate response to calls and e-mails to German Embassy spokesmen. The state security bureau’s phone number is unlisted.