BEIRUT, Lebanon — Saudi Arabia lashed out at Canada on Monday for criticizing the recent arrests of Saudi rights activists, and threatened to break off trade with other Western countries if they too spoke out about political repression in the kingdom.

The unusually harsh response by the Saudi government was the latest evidence that while Crown Prince Mohammed bin Salman is promoting himself as a reformer, championing the loosening of conservative social norms and opening the economy, he is also prepared to punish any perceived challenge to his authority at home or abroad.

Faced with economic troubles at home, and a restless, young population, the crown prince has carried out a crackdown that is extraordinary even by the standards of an absolute monarchy that has never allowed much room for free speech.

After what once would have passed as a pro forma complaint from Canada, Saudi Arabia expelled the Canadian ambassador, withdrew its ambassador from Canada and froze new business deals and investment with Canada.