Chinese authorities have detained dozens of people as part of a ramped-up annual crackdown ahead of the anniversary of the Tiananmen Square massacre. Tuesday will mark 30 years since the bloody event, which saw Chinese authorities brutally shut down long running student protests, killing thousands of people in and around the central square in Beijing. Chinese Human Rights Defenders (CHRD), a US-based organisation for domestic and international activists, said the Beijing government’s “pre-emptive strikes” against anyone who might try to mark the anniversary had started in early May.