A Labour MP has caused outrage by suggesting that Britain's first Jewish ambassador to Israel has divided loyalties because he has "proclaimed himself to be a Zionist".

Challenged by the JC to clarify his comments about Matthew Gould, who took up the post last year, Paul Flynn, the Labour MP for Newport West, said ambassadors to Israel had not previously been Jewish "to avoid the accusation that they have gone native".

Britain needed, he said, "someone with roots in the UK [who] can't be accused of having Jewish loyalty".

The Foreign Office and MPs from across the political spectrum sprang to Mr Gould's defence and condemned the remarks.

Middle East Minister Alistair Burt said: "Paul Flynn should take some time to consider his comments, which could easily be misconstrued. There is absolutely no reason why our ambassador to Israel should not be Jewish. Any allegations about Matthew Gould's conduct are utterly unsubstantiated. He is a first-class ambassador."

Douglas Alexander, the Shadow Foreign Secretary, said: "The faith of any British diplomat is irrelevant to their capability to their job. To make suggestions otherwise is wrong and offensive.

"On a personal note I know from my time in government Matthew Gould embodies all that is good in British diplomacy."

Mr Flynn's initial comments came during an inquiry last Wednesday by the Public Administration Select Committee into the role of the head of the civil service. The present incumbent of the post, Sir Gus O'Donnell, was being questioned about his investigation into Adam Werritty, the controversial adviser to former Defence Secretary Liam Fox.

Mr Flynn asked about meetings between Mr Werritty and Mr Gould. Mr Gould previously served as a diplomat in Iran and some reports have speculated that he, Mr Werritty and Dr Fox discussed a potential military strike on Iran with Mossad.

"I do not normally fall for conspiracy theories, but the ambassador has proclaimed himself to be a Zionist and he has previously served in Iran, in the service," said Mr Flynn.

He said doubts had been raised about Mr Gould's loyalty by two of his constituents, Pippa Bartolotti and Joyce Giblin, who had been held in prison in Israel after taking part in the "flytilla" demonstration against the Gaza blockade in July.

"When they were briefly imprisoned in Israel, they met the ambassador, and they strongly believe… that he was serving the interest of the Israeli government, and not the interests of two British citizens," he told the committee.

Ms Bartolotti is the deputy leader of the Green Party in Wales and stood against Mr Flynn at the last election.

Mr Flynn's fellow committee member, Robert Halfon, MP for Harlow, objected to the comments: "Mr Flynn is implying that the British ambassador to Israel is working for a foreign power, which is out of order."

Mr Flynn told the JC he was asking for transparency about the Werritty-Gould meetings because he was worried that "neo-cons and war-mongers" were fomenting war against Iran.

He said he stood by his comments to the committee, including his questions about Mr Gould's loyalty to the UK.

"In the past there hasn't been a Jewish ambassador to Israel and I think that is a good decision - to avoid the accusation that they have gone native."

Mr Flynn added that the same question of divided loyalty would apply to anyone with a "foreign" family background, including former Foreign Office Minister Denis MacShane, whose father was Polish.

"Imagine Denis MacShane as ambassador to Poland? Heaven forbid," Mr Flynn said.

But the MP insisted that he was a friend of Israel and had visited the country four times, including once with his family on holiday.

Louise Ellman, Labour MP for Liverpool Riverside, said: "I am astounded by these unfounded insinuations. Matthew Gould has a high reputation as an outstanding representative of the UK government."

In a joint statement, the Board of Deputies and the Jewish Leadership Council said: "It is deeply disturbing to suggest that certain parts of public service are out of bounds for British Jews and a slur on the professionalism of a British ambassador who is widely recognised for effectively representing Britain's interests."

On her discussions with Mr Flynn, Ms Bartolotti said: "I questioned the wisdom of having a Jewish Zionist ambassador in Israel and stated that their loyalty was a matter for the FCO to investigate.

"I also questioned the motive for keeping British citizens in jail without charge, when the Australian consul had intervened and the two Australian women were allowed passage to Bethlehem.

"My grandfather was Jewish, I have no problems with Jews or Isaelis."

Ms Bartolotti added: "The Vice -Consul was called Levi. From the university of life I have learned that Jews often have a conflict of interest in matters relating to Palestine.

"That does not make them bad people (we all experience some form of bias).

"It does, however, leave them open to criticism when travellers such as myself are prevented from visiting Palestinian people.

"I would also add that when I filled a van with dental equipment for my sucessful overland trip to Gaza, most of the donations came from good-hearted British Jews - information I was glad to pass on to the people of Gaza."