Bob Hawke remains at Royal North Shore Hospital tonight after being admitted yesterday afternoon.

His wife Blanche d'Alpuget, who visited her husband in hospital today, says his condition is nothing more serious than a case of "the wobbles".

A spokesperson for the former prime minister said earlier today that Mr Hawke was "doing fine and hopes to be discharged within the next 24 to 48 hours".

Mr Hawke's wife Blanche d'Alpuget visited him at Sydney's Royal North Shore Hospital on Tuesday morning (9NEWS) (9news)

A spokesperson for Mr Hawke said 'he's doing fine and is hoping to be discharged in the next 24 to 48 hours'. (9NEWS) (AAP)

It is not yet known what Mr Hawke is being treated for, but Ms d'Alpuget has denied reports he suffered a stroke or has pneumonia.

Earlier this morning, former Labor senator Sam Dastyari said there were concerns for Mr Hawke's welfare, divulging a conversation he had with Ms d'Alpuget at the weekend.

Mr Dastyari told Sydney radio station KIIS FM that he visited Mr Hawke on Anzac Day "for a few beers on the porch".

"The reality is he's 88, and when you're 88 and get rushed to hospital, people are worried and there is reason to be worried," Mr Dastyari said.

Mr Hawke attended Kim Beazley's swearing in ceremony in Perth just last week. (AAP) (AAP)

Former senator Sam Dastyari has revealed a conversation he had with Mr Hawke's wife Blanche d'Alpuget. (AAP) (AAP)

"I was actually meant to be having dinner with Bob and Blanche at this great restaurant in Sydney on Saturday night.

"And Saturday afternoon, Blanche calls and says 'look, Bob's just not feeling up to it, can't do dinner tonight and can we do it another time'."

Arguably Australia's most popular politician and prime minister, Mr Hawke celebrated his 88th birthday in December last year .

The most electorally successful Labor leader in Australian history, Robert James Lee Hawke held office as the 23rd Prime Minister of Australia from 1983-1991, leading the Labor Party to four consecutive electoral victories.

He was first elected as Prime Minister in 1983. (AAP) (AAP)

Bob Hawke and Nelson Mandela in a photo taken in 1990. (AAP) (AAP)

His major achievements in office include the creation of Medicare, the formation of APEC, and the initiation of national super.

Mr Hawke has maintained an active role in political life, attending Labor rallies and lending support to recent leaders including Kevin Rudd and Julia Gillard.

Only last Tuesday, he flew to Perth to watch former leader of the national Labor party, Kim Beazley, sworn in as Governor of Western Australia.