A top spokeswoman for US president Donald Trump has said she misspoke when she referred to a 2011 "massacre" in Kentucky that never happened.

A day earlier, during an interview with MSNBC's Chris Matthews, Kellyanne Conway defended Mr Trump's temporary ban on immigration from seven Muslim-majority nations by saying that former president Barack Obama had instituted a similar policy for Iraqi refugees in 2011.

"President Obama had a six-month ban on the Iraqi refugee programme after two Iraqis came here to this country, were radicalised, and they were the masterminds behind the Bowling Green massacre," Ms Conway said.

"Most people don't know that because it didn't get covered."

The incident she referred to never took place.

Ms Conway tweeted on Friday morning that she meant to say "Bowling Green terrorists" during the interview.

Her description of the 2011 Obama administration policy as a ban was also a mischaracterisation, which she did not correct.

Mr Obama never banned Iraqi refugees or other Iraqi travellers from coming to the United States. His administration did slow down the processing for Iraqis seeking special immigrant visas, which are given to translators and interpreters who worked with the US in that country.

The slowdown was prompted by the May 2011 arrest of two men in Kentucky charged with plotting to send weapons and money to al-Qaida operatives abroad. Waad Ramadan Alwan and Mohanad Shareef Hammadi were mistakenly admitted to the US as Iraqi refugees in 2009 and resettled in Bowling Green, Kentucky.

Alwan and Hammadi are in prison after pleading guilty to plotting attacks inside the US.

According to US state department data, 9,388 Iraqi refugees were admitted to America during the 2011 budget year. The data also show that Iraqi refugees were admitted every month during the 2011 calendar year.

In addition, more than 7,800 Iraqis were allowed into the United States on non-immigrant visas, including tourists, during the 2011 budget year.