Former prime minister Dr Mahathir Mohamad admitted that there was corruption during his administration but said Prime Minister Najib Abdul Razak has now taken things to an all new level.

Mahathir said this during an interview with Al Jazeera's UpFront host Mehdi Hasan, who grilled him about corruption when he was prime minister as well as his campaign against Najib.

"There is corruption in every country. It is the level that counts. I admit that during my time, there was corruption.

"But not on the scale that Najib is involved in, running into billion and billions - tens of billions of ringgit.

"That has never been done or heard of in this country," he said.

Mahathir also defended his own record, stating that if he was corrupt, the country would not have prospered.

"A country that is corrupt cannot make progress.

"During my time, the country did very well. It became very prosperous and the people were happy to support the government - my government - every election for five elections and I won by two-thirds majority," he said.

Mahathir added that he was powerless now and if indeed the claims of corruption against him were true, he would have been hauled up to court.

Mahathir also defended his campaign to oust Najib, stating that the prime minister has shut down democratic avenues for redress.

"If Najib is there, this country will go to the dogs," he said.

The interview was aired today and is also available on Al-Jazeera's website.