NEW YORK -- The Simon Wiesenthal Center says tech giants Facebook and Twitter are making efforts to police terrorists and hate groups on their sites but more work needs to be done.

The organization released its annual digital terrorism and hate report card in New York City on Tuesday.

The group gave a B-plus to Facebook, a B-minus to Twitter and a C-plus to Google. Representatives for the three companies did not immediately return emails seeking comment.

Wiesenthal Center senior researcher Rick Eaton showed posts on Facebook-owned Instagram urging violent attacks at the upcoming World Cup in Moscow.

He said such posts are quickly taken down but not before promoters of terrorism get their message across.

The Los Angeles-based Wiesenthal Center is dedicated to fighting anti-Semitism, hate and terrorism.