Twitter UK general manager Tony Wang has announced he is to step down from the role and return to the US.
The move comes after Twitter UK was rocked by the use of anonymous Twitter accounts to make threats against Labour MP Stella Creasy, campaigner Caroline Criado-Perez and several female journalists.
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In August, Wang apologised to women who had been attacked by "trolls" on the microblogging site.
After the threats, Twitter updated its rules to make it clear that abuse will not be tolerated, put extra staff in place to handle reports of abuse and added a “report” button to the service.
Commenting on his departure, Wang tweeted: "2+ years, 15MM users in UK, teams in 6 EU countries, excited to return to HQ and home. Proud to hand off to incredible European leadership!"
Wang launched the Twitter London office in 2011 and played a key role in the growth of the sales support team in Europe.
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He is to return to the US to focus on “new projects”, according to the Telegraph.
Wang’s London role is to be taken over by UK sales director Bruce Daisley, who joined Twitter from Google last year.
Daisley has played an important role in signing up hundreds of UK brands to use Twitter’s "promoted" products to reach customers, according to The Drum.
Wang’s departure coincides with a number of new appointments at Twitter UK, including the Guardian’s social media and communities editor Joanna Geary as its first news partnerships manager, and former BBC Sport editor Alex Trickett as sport partnerships manager.
Twitter claims it has more than 200 million active users worldwide, including 15 million active users in the UK, up from 10 miIlion in May 2012.