An Egyptian journalist who was due to receive a US medal of honour had her award postponed and was put under investigation by White House officials after she was accused of supporting terrorist activity.

Samira Ibrahim was due to receive the International Women of Courage Award next Thursday from Secretary of State John Kerry and First Lady Michelle Obama in recognition of her work exposing "virginity tests" conducted by the Egyptian army during the Tahrir Square protests last year.

However, critics challenged the decision to honour Ms Ibrahim after she allegedly made comments supporting Hitler and terror attacks against the US and Israel on Twitter.

Yesterday, State Department spokesperson Victoria Nuland said that Ms Ibrahim's award would be postponed while officials investigate the tweets.

"We became aware very late in the process about Samira Ibrahim's alleged public comments," said Ms Nuland. "In conversations with us in the last 24 hours, Ms. Ibrahim has categorically denied authorship. She asserts that she was hacked. But we need some time, and in order to be prudent, to conduct our own review."

According to a news report on Ahram Online, Ms Ibrahim claimed her Twitter page has been "hacked more than once and any tweet about racism or hatred was not mine."

Writing in the Weekly Standard, American-Egyptian Samuel Tadros, a researcher at Hudson Institute's Centre for Religious Freedom, recorded the comments that have now been removed.

One tweet on the attack against Israelis in Bulgaria, attributed to Ms Ibrahim, read: "An explosion on a bus carrying Israelis in Burgas airport in Bulgaria on the Black Sea. Today is a very sweet day with a lot of very sweet news."

"Today is the anniversary of 9/11," read another tweet allegedly posted by Ms Ibrahim last year. "May every year come with America burning."

Last August a message also allegedly by Ms Ibrahim quoted Adolf Hitler, saying: "I have discovered with the passage of days, that no act contrary to morality, no crime against society, takes place, except with the Jews having a hand in it."

According to US officials, Ms Ibrahim - a coordinator of the Know Your Rights movement in Egypt - was arrested in secondary school after criticising "Arab leaders' insincere support of the Palestinian cause."