A postman was caught on CCTV muttering horrific racist language as he waited for an elderly man to answer the door in Manchester .

In the footage, the Royal Mail worker is heard saying: "Come on you black c***, hurry up. Open your f*****g (inaudible)".

He then hums a tune as the door opens before he delivers the parcel.

The incident happened on Tuesday afternoon (January 14).

A spokesman for Royal Mail said they have a 'zero tolerance approach' to racism and will launch an 'immediate investigation'.

The homeowner, Sardar Singh, 70, did not hear the racist language.

But the house is fitted with a 'smart doorbell', which records video and audio footage when someone rings it.

His son, Ben Singh, was alerted to the recording as it is linked up to his phone.

The 35-year-old, who works in finance, said: "It was awful. My dad is an older man. He's quite frail, he has a walking stick. We are British born. I'm disgusted, appalled, outraged.

"(The postman) would have been looking at my dad when he said 'come on you black c***'.

"I was listening to it in live time. I was gobsmacked. I went back over it and it is crystal clear.

"I'm just bewildered. That's just unacceptable. The C word is bad enough. I have called the 101 service, they think it is a serious hate crime. I have spoken to Royal Mail complaints, they are taking it seriously.

"(My dad) is worried. My dad is frightened to open the door."

A spokesman for GMP said: "At around 4.15pm on Tuesday, January 14, police were called to reports of a hate incident. Enquiries are currently ongoing."

A spokesman for Royal Mail said: "Royal Mail has a zero tolerance approach to any form of abuse, including racism.

"We expect the highest standards of behaviour from our people while out on deliveries and collections at all times.

"We have launched an immediate investigation into this matter. Once that investigation is complete, we will be taking the most appropriate action in accordance with our business conduct code”.