The posts, from 2012 and 2013 when Robinson was a teenager, were revealed while he was making his England debut during the drawn first Test against New Zealand at Lord's.

Robinson, 27, has been dropped for the second Test, which begins at Edgbaston on Thursday, pending an investigation.

Culture Secretary Oliver Dowden asked the ECB to "think again".

Dowden said the tweets were "offensive and wrong" but "also a decade old and written by a teenager".

A spokesperson for Mr Johnson said: "The PM is supportive of Oliver Dowden's comments. As Dowden set out, these were comments made more than a decade ago written by someone as a teenager and for which they've rightly apologised."

The ECB will not be making any comment about Dowden's stance.

The tweets, posted when Robinson was aged 18 and 19, came to light on Wednesday afternoon, while he was on the field.

After play, he apologised, saying he was "embarrassed" and "ashamed".

"I am sorry, and I have certainly learned my lesson today," he said. "I want to make it clear that I'm not racist and I'm not sexist."

The ECB must determine whether Robinson was contracted at the time of the tweets, which cover a period when he left Kent and joined Yorkshire.

If he did not have a contract, the investigation will be carried out by the ECB. If Robinson had a county contract at the time, the Cricket Discipline Commission, which is independent of the ECB, will carry out the investigation.

Speaking to BBC Radio 5 Live, former England captain David Gower agreed with Dowden, saying he did not think a suspension was the right way forward.

"The ECB should say 'let's learn from this' and make him do the equivalent of community service," said Gower.

"He should go out there among county cricketers and spread the word that social media shouldn't be abused."

However, Michael Carberry, who played six Tests for England between 2010 and 2014, told BBC Radio 5 Live that Robinson "wouldn't be playing Test cricket" if it was up to him.

"I don't believe this is a problem where you can rehabilitate someone," said Carberry.

"Robinson spoke about educating himself, but what is he talking about? I would be very interested to know."

At the conclusion of the match on Sunday, England captain Joe Root said the tweets were "not acceptable".

"Ollie has made a huge mistake," Root told BBC Test Match Special. "He fronted up to the dressing room and the rest of the world, and he's very remorseful."

Robinson returned match figures of 7-101 and scored 42 in his only innings against New Zealand.

Former England captain Michael Vaughan told BBC Sport: "He has got to go away, learn and educate himself - and become a better person for it.

"In terms of what he has delivered on the cricket field, he is a Test-match player. He will certainly be back playing Test cricket."

On the morning his tweets were shared online, England shared a 'moment of unity' with the tourists, with Root's side wearing T-shirts carrying messages of anti-discrimination.

"It's a lesson to everyone in the game," added Root. "More has to be done, that continued education and learning about how to behave in society and within our sport.

"We've started doing a lot of good work as a team and we'll continue to do that. We want to make the game as inclusive and diverse as we possibly can and we'll continue to keep looking at finding ways to make that possible."

The Prime Minister's spokesperson added he "respects people's right" to take the knee, after the England football team were booed for the gesture during their recent friendly matches against Austria and Romania.