PLO Jerusalem Affairs Chief Sari Nuseiba, legislator Jawad Buloos, and two others were detained by Jerusalem police this morning as they were about to begin hosting a diplomatic reception at a Jerusalem hotel. Nuseiba had invited consular representatives from many countries for the PLO-sponsored reception to mark the Moslem holiday Id al-Fitr. Public Security Minister Uzi Landau told Voice of Israel Radio this morning that the police are instructed to prevent any official PLO activity in the nation\'s capital. Landau said that an official PLO reception in Jerusalem, like the activity in the now-closed Orient House, constitutes a grave violation of Israel\'s sovereignty in its own capital.