Former Republican vice-presidential nominee Sarah Palin has called for all immigrants to the United States to “speak American”.

Ms Palin, popular among conservatives in the US, weighed into the debate sparked by controversial comments from Donald Trump about Jed Bush speaking Spanish, reported The Guardian.

“It’s a benefit of Jeb Bush to be able to be so fluent in Spanish, because we have a large and wonderful Hispanic population that is helping to build America,” Palin told CNN’s State of the Union.

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“On the other hand, you know, I think we can send a message and say: ‘You want to be in America? A, you better be here legally, or you’re out of here. B, when you’re here, let’s speak American’.

“I mean, that’s just, that’s – let’s speak English.”

Ms Palin was John McCain’s running mate in the 2008 presidential race. She went on to say that “the most unifying aspect of a nation is the language that is understood by all”.

Despite her opposition to the use of foreign languages, she admitted she learnt to speak French and Spanish in high school, however she mastered neither because she “got them all mixed up”.

Ms Palin added there might be a possibility she’d like to be appointed energy secretary if Trump wins the presidency.

“I think a lot about the Department of Energy, because energy is my baby, oil and gas and minerals,” Ms Palin said.

“Those things that God has dumped on this part of the Earth for mankind’s use, instead of relying on unfriendly foreign nations for us to import their resources.

“And if I were head of that,” she said in regards to the department, “I would get rid of it.”

Here’s video of what Ms Palin had to say: