Thursday 15th November 2012 by Patrick Davies | Photos by WENN

Tags: Jay-Z

Robert De Niro reportedly branded Jay-Z "disrespectful" at Leonardo Di Caprio's birthday party.

The pair were both in attendance at the A-list bash on Saturday, when De Niro allegedly slammed the rapper for not returning his calls.

An insider told The New York Post: "Bob was sitting at a table, and when Jay-Z went over to say hello, De Niro told Jay that he never called him back."

The spat apparently started because Jay-Z had agreed to record a track for the Tribeca Film Festival - an event that De Niro is heavily involved in.

The song never came to fruition, but according to the New York Post the actor desperately tried to contact Jay-Z to resurrect the agreement - but he never received a response.

De Niro in Paris earlier this year

The insider went on to claim that De Niro had phoned the 42-year-old six times with no response, which also prompted him to call the '99 Problems' star "rude".

They added: "Bob wasn't in any mood to make polite conversation. He told Jay that if somebody calls you six times, you call them back. It doesn't matter who you are, that is just rude."

The event took place at New York club, The Darby on Saturday night to celebrate Di Caprio's 38th birthday.

Another source said: "De Niro kept telling him that he thinks he's the man, but that he was disrespectful."

It is reported Jay-Z's wife Beyonce attempted to diffuse the situation - before the rapper tried to explain himself by saying he 'isn't great over the phone'.

Neither of the two stars have commented on the incident but others who were close to the scene have stressed the exchange amounted to nothing more than a "low-key conversation".

Other high profile names at the party included Jamie Foxx, Cameron Diaz, and Chris Rock.

See the video for Jay-Z's New York inspired single 'Empire State of Mind' featuring Alicia Keys below.