Christian groups in the US have demanded that the British ambassador to the country should be sent home after gay Tory MP Alan Duncan failed to apologise over a joke about murdering Miss California Carrie Prejean.

They have also called for President Barack Obama to temporarily sever diplomatic relations with Britain.

Ms Prejean had been asked by blogger Perez Hilton her thoughts on gay marriage at the Miss America contest last week.

She replied: “I believe that a marriage should be between a man and a woman.”

Appearing on BBC news quiz Have I Got News for You on Friday, Mr Duncan called her a “silly bitch” and joked: “If you read that Miss California has been murdered, you will know it was me, won’t you?”

According to Ms Prejean’s publicist, her family have received several death threats since the programme was broadcast.

A spokesperson at her PR company said that she had cancelled all plans to visit England.

Christian Groups and other bodies such as Public Advocate are lobbying President Obama and say they may start to lobby The Queen over Mr Duncan’s comments.

Public Advocate president Eugene Delgaudio said: “Public Advocate is concerned when government officials from abroad advocate murdering our citizens.

“The British Ambassador in Washington should be sent home immediately and the President of the United States should sever diplomatic relations for a period of time.

“Alan Duncan is not from the United States, he probably doesn’t understand our way of life. He is not an American, not a party to American politics, and yet he is trying to limit one American’s right to free speech.

“Attempting to silence one American is an attempt to silence all Americans.

“How is Duncan’s murder threat any different from King George’s threat to put down the Boston Tea Parties and the American revolution?

“Long live free speech and long live the reign of Miss California.”

Ms Prejean’s pastor at the Rock Church, Miles McPherson, confirmed that she had received death threats and said: “You cannot say it was a joke. The man is a leading politician who may soon have great government power.

“Murder is murder in any context.”

He added: “I have prayed to forgive him and bless him. Also his boss [David Cameron]. They both need Jesus in their lives and I pray that Alan Duncan and his boss turn to Jesus”.