Germany warned of "immediate consequences” if Thailand’s King Maha Vajiralongkorn broke the law on its soil as thousands of protesters gathered outside its embassy in Bangkok on Monday, stepping up the pressure in their campaign for changes to the monarchy.

The demonstrators submitted a letter questioning the king’s legal status in the European country and asking Germany to probe whether he has exercised royal authority during his time there in violation of the country’s law. The petition is meant to help Thailand return "to the path of truthful constitutional monarchy,” according to a joint statement issued by protest organizers.

"We have not only been looking into that in recent weeks, but on a regular basis,” German Foreign Minister Heiko Maas said at a news conference. "If there are things we consider to be illegal, that will have immediate consequences.”