Turkey has been on edge since demonstrators expressed frustration over plans to raze a historic park in Istanbul. Demonstrations this year have evolved into a national anti-government campaign.
Human Rights Watch said Wednesday it documented 10 cases in which demonstrators were injured seriously by tear gas canisters fired at close range by Turkish police.
Turkey researcher Emma Sinclair-Webb said tear gas can leave dramatic scars when fired directly at protesters.
"The police and their commanders who used these canisters in such an irresponsible way should be held to account for inflicting unnecessary harm and endangering lives," she said in a statement.
The European Court of Human Rights ruled against Turkey in a case this week involving the use of tear gas in 2006 demonstrations in support of the militant Kurdistan Workers' Party. Turkish police fired tear gas canisters directly at protesters, the court found.
Human Rights Watch reported similar incidents during demonstrations this year. It said the Turkish government has distributed pamphlets instructing police on riot-control guidelines but says nothing about how and where to fire tear gas canisters.