Twitter director of communications Matt Graves denied allegations that the microblogging site has censored WikiLeaks tweets from its list of Trending Topics, media news site Mashable reported on Monday.

Ever since the whistleblower site started putting out thousands of classified documents on its site, there have been thousands of tweets about the documents. However, the site has deliberately kept off the tweets from its hot topics list, media reports said.

A blogger who compiled a list of trending topics from Twitter trending analysis tool Trendistic.com, said that WikiLeaks has not been a trending topic on Twitter since 21 August.

There are several factors that may come into play when seemingly popular terms don't make the Trends list, Twitter said in a note to Mashable.

"Sometimes topics that are popular don't break into the Trends list because the current velocity of conversation (volume of tweets at a given moment) isn't greater than in previous hours and days.... And, on occasion, topics just aren't as popular as people believe," the site added in the note.