More than 20 people have been injured and tens have been detained in Istanbul during May Day protests.

Episodes of unrest began after police used tear gas and water cannon to warn citizens against staging a banned demonstration on Taksim Square, which saw a wave of anti-government action last year.

Both Prime Minister Recep Tayyip Erdogan and the Istanbul Governor's Office declared protests will not be allowed for Labor Day, citing reports that "illegal terrorist groups" would exert violence against security forces in order to incite riot.

Turkey's trade unions vowed to stay on Taksim square despite "the irrational and illegal ban," as their statement was quoted by the BBC.

Demonstrations are also ongoing in Turkey's capital Ankara, where clashes with police have resulted in a few people being detained, according to Hurriyet Daily News.

A total of over 30 Turkish provinces are set to stage May Day activities.

Istanbul's Taksim prompts grim recollections on 1 May, after 34 people were killed at a union members demonstration on the square in 1977. Celebrating the day there was later declared illegal.