Greenpeace activists have hung a banner defending people's right to protest from a construction crane close to Spain's Parliament as part of activities to highlight the coming into effect of the Public Security Law, known as the "gag law," July 1.

Greenpeace draped the banner, which read "Protesting is a Right" early Tuesday on a crane located just behind the lower house in Madrid.

Social activists plan protests up to and around midnight against the law, which has been criticized by human rights groups, international observers and opposition parties.

The law allows for the summary expulsion of migrants caught illegally entering the country's North African enclaves, sets hefty fines for protests outside Parliament or strategic installations and provides for banning unauthorized television and photographic images of police.