Many British voters have had a few choice words for Sir Keir Starmer – but in Iran, the Prime Minister is unable to avoid a rather unfortunate nickname.

To millions of Persian speakers, his first name sounds remarkably similar to a vulgar term for a penis. The word کیر – transliterated as “kir” – is one of the language’s most commonly used obscenities.

The linguistic similarity, long noted by Iranian diaspora communities, has sparked a wave of mockery on social media since the outbreak of the Iran war.

Sir Keir’s perceived passivity during escalating tensions in the Persian Gulf has given Iranian users fresh ammunition, and they have used his name as a punchline for their criticism.

“From his name, you can tell what kind of man he is,” one user wrote on X.

While the joke predates the Iran war, the volume increased in the past month, and peaked this week when Sir Keir declared that Britain would not take part in any blockade of the Strait of Hormuz.

The Prime Minister’s widely shared statement prompted an immediate eruption of jokes online, with many Persian speakers referring to him as “Kir Starmer”.

One wrote: “So this Kir Starmer made fools of us! Uncle, we know!” Another said: “If Starmer was any good, his mother wouldn’t have named him Kir.”

Sir Keir’s decision to flip-flop on allowing US access to British RAF bases has endeared him to neither Washington nor the opposition in Iran.

Iranian dissidents and opposition figures accused the Prime Minister of having it both ways – distancing himself from the war in public statements while enabling it from British soil.

Reza Pahlavi, the former crown prince of Iran has been among those to attack Sir Keir’s position, accusing him of effectively “appeasing” the Islamic Republic.

Donald Trump has made the Prime Minister a frequent target, and last month the US president said of him: “This is not Winston Churchill that we’re dealing with.”

Mr Trump has also compared him to Neville Chamberlain for his perceived strategy of appeasement.