The Liberal Democrats have "immediately opened disciplinary investigations" into tweets allegedly sent from one of their General Election candidates.
The party added that Kevin McNamara has resigned as the candidate for Thurrock "with immediate effect".
Mr McNamara released a statement on Monday night saying he is "deeply sorry" for the comments he made.
The tweets, reportedly posted between 2009 and 2010, allegedly use racist and homophobic slurs.
In a statement, Mr McNamara said: “I am deeply sorry for the comments that I made that are currently being reported in the press.
"These words are deeply offensive and I apologise profusely to everybody that I have offended with these tweets.
“I would never want to undermine the voices of those communities with slurs or degradation and it’s important that people who want to represent the public are held to the very highest standard.
!I am resigning as a candidate with immediate effect for the upcoming election.
“I apologise to all of those I have let down with my past conduct and will work hard to regain their trust.”
His account has now been locked and tweets are not visible.