Not getting refresh token from Github oauth

I am using Passport for oauth and getting access token successfully, but I'm unable to get the refresh token even after setting the access_type to offline. The access_type parameter is not appended to the url on Github Login page. Code is given below:

passport.use(new GitHubStrategy({
        clientID: 'client_id',
        clientSecret: 'client_Secret',
        scope: 'repo,user',
        access_type: 'offline',
        approval_prompt: 'force',
        callbackURL: "http://localhost:3000/auth/github/callback"
    },
  function(accessToken, refreshToken, profile, done) {
      token = accessToken;
      console.log("accessToken: "+accessToken+"   refreshToken: " +refreshToken+"  profile "+JSON.stringify(profile));
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