Web giants including Facebook have struck a deal with advertisers on how to identify harmful content such as hate speech, after an impasse over the issue which led to boycotts of the platform.

The agreement -- which also included Twitter and YouTube -- laid out for the first time a common set of definitions for hateful statements online.

In July, hundreds of advertisers including big-name consumer brands suspended advertising with Facebook as part of the #StopHateForProfit campaign, saying the social-media titan should do more to stamp out hatred and misinformation on its platform.

And earlier this month a group of celebrities -- including Kim Kardashian, Leonardo DiCaprio and Katy Perry -- stopped using Facebook and Instagram for 24 hours, to push a similar message.

The World Federation of Advertisers (WFA) said in a statement Wednesday: "Facebook, YouTube and Twitter, in collaboration with marketers and agencies through the Global Alliance for Responsible Media have agreed to adopt a common set of definitions for hate speech and other harmful content and to collaborate with a view to monitoring industry efforts to improve in this critical area."

The alliance was founded by the WFA and includes other major trade bodies. According to the WFA, key areas of agreement included applying the alliance's common definitions of harmful content; developing reporting standards for such content; establishing independent oversight; and rolling out tools for keeping advertisements away from harmful content.

The WFA said that properly defining online hate speech would remove the current problem of different platforms using their own definitions, which it said made it difficult for companies to decide where to put their ads.

"As funders of the online ecosystem, advertisers have a critical role to play in driving positive change and we are pleased to have reached agreement with the platforms on an action plan and timeline in order to make the necessary improvements," said Stephan Loerke, chief executive of the WFA.

Luis Di Como, executive vice-president of global media at Unilever, a major advertiser, sounded a note of cautious optimism.

He said: "The issues within the online ecosystem are complicated, and whilst change doesn’t happen overnight, today marks an important step in the right direction."

Speaking in July, Facebook's founder and chief executive Mark Zuckerberg said he remained adamant that the company did not want hate speech on the social network.

On Wednesday, the company's vice-president for global marketing solutions, Carolyn Everson, said the agreement gave all parties "a unified language to move forward on the fight against hate online."