Former Malaysian prime minister Najib Razak said Finance Minister Lim Guan Eng should stop "playing politics with inflated guesstimates" when talking about the country's financial position, and instead concentrate on safeguarding economic growth and financial stability.

Writing on his Facebook account, Datuk Seri Najib who was ousted in the general election last month, said Mr Lim should ensure that Malaysia remained on course to achieve high-income status, which the World Bank and International Monetary Fund had said could be achieved in three years' time.

Returning to a topic which he had written about before, Mr Najib who was also Malaysia's finance minister, said Mr Lim should make public studies carried out on the cancelled high speed rail (HSR) link to Singapore, in the name transparency.

Mr Lim was appointed finance minister by the Pakatan Harapan (PH) government and has been giving regular updates about Malaysia's debts which totalled RM1 trillion (S$340 billion), against what Mr Najib said was the "official debt" figure at RM686.8 billion.

"In the past week, Lim has continued to cite various figures that are not accurate and can only be viewed to be politically motivated," Mr Najib wrote in a lengthy posting.

"The elections are over. You have won and we have lost," he said. "The focus should now be to safeguard our country's economic growth, jobs and financial stability - not playing politics with inflated 'guesstimates' to provide an excuse for not delivering on PH's manifesto as per your promised timeline".

Mr Lim has announced that five of 10 proposals in PH's election manifesto would be delayed, while the PH chairman, Prime Minister Mahathir Mohamad has acknowledged that the government found it difficult to meet the target of 100 days to deliver all its promises due to the surprise discovery of high government debts left behind by Mr Najib.

The new government has also decided to scrap the HSR, which was signed off by the Najib administration to curb spending.

Mr Lim said in an interview with the South China Morning Post that he could get the HSR built " cheaper, for half the price."

"What we are seeing are projects that are double the market price," Mr Lim said.