KUALA LUMPUR - Prime Minister Najib Razak on Sunday vowed to stand firm and defy calls for him to resign even as he faces mounting pressure to step down over his handling of the debt-laden state fund 1Malaysia Development Bhd (1MDB).

"I will not bow to pressure. I will not quit as Prime Minister or Umno president," Datuk Seri Najib was quoted saying by The Star newspaper during a speech in front of a 40,000-strong crowd in Tawau, Sabah on Sunday.

"I have the mandate and I will continue my struggle for the people," he said.

Najib, who is 1MDB's adviser, has in recent months been under pressure amid public calls for his resignation from former Prime Minister Mahathir Mohamad over Najib's management of 1MDB.

He was under renewed scrutiny last week, after it was reported that pilgrim fund Lembaga Tabung Haji had confirmed buying land from 1MDB.

On Thursday, Tabung Haji, a federal body that manages funds saved by Muslims for pilgrimages to Mecca, said in a statement that it had bought the 0.64ha piece of land in the Tun Razak Exchange (TRX), Kuala Lumpur's new financial district, for RM188.5 million (S$69.6 million) from 1MDB. The statement came after details of the purchase was put up on a blogsite and went viral on social media.

Taking a swipe at Mahathir on Sunday, Najib said, "No individual has the right to ask the removal of a democratically elected leader."

He said Mahathir had remained prime minister and president of ruling party Umno for 23 years because the party gave him the full support no matter what crisis hit his administration.

"If Umno did not give him the support, would he have lasted 23 years as president and prime minister?" Najib asked.

Regarding Dr Mahathir's claims that 1MDB was losing money, he said that it was only a matter of time for them to solve the problems.

Najib also denied that the land purchase from 1MDB was a bailout, saying the issue was manipulated to make it look like pilgrims' money was used to save the state fund.

He clarified that the purchase of land from 1MDB was an investment and not a bailout. "Because of the controversy raised, I advised Tabung Haji to sell the land," he added

"We do not want to continue with this controversy because it will take away a lot of our energy in terms of concentrating on some of the big programmes that we have in mind," Najib was quoted as saying.

His comments followed the announcement by Tabung Haji chairman Abdul Azeez Abdul Rahim that the fund planned to sell the land. Azeez said the prime minister had advised him to dispose of the land so that the fund's reputation is not "tarnished" due to its business transaction with 1MDB, the Malaysian Insider reported.

Najib said turning the land over to the private sector was a good commercial deal, which would see Tabung Haji make a few million ringgit overnight, Bernama reported.

"So, it cannot be a bailout (for 1MDB). No private company will buy over a project if it is going to lose money," he said.

The land will be sold to a buyer at a profit of at least RM5 million and will be concluded within the next few weeks, the Malaysian Insider quoted Azeez as saying on Friday.

He said Tabung Haji bought the land with the view of developing a residential tower that could have yielded a profit of RM180 million within three years.

"We will find another land to invest in. This proves that this plot of land is not difficult to sell. We only held the title for a month and it is still profitable for us," he said.

1MDB has been mired in controversy since the end of last year after it was revealed that it had racked up RM42 billion in debt - over a third of which is guaranteed by taxpayers. A close associate of Najib has been accused of siphoning off close to RM4 billion from 1MDB.

Opposition lawmakers have also been demanding Najib's resignation, as he is also the finance minister and chairman of 1MDB's advisory board.

Parti Keadilan Rakyat (PKR) vice-president Nurul Izzah Anwar said on Sunday that Najib should resign and Tabung Haji top executives be sacked over the land purchase, the Malaysian Insider reported.

"To be fair all heads must roll in Tabung Haji including the prime minister, because he remains as the 1MDB advisory board chairman," Nurul Izzah was quoted as saying.

She also said the issue should serve as a wake-up call, especially to Umno leaders.

"Are you going to tell me all of you will stay silent in the face of such unacceptable transaction? It should serve as a wake up call, especially to Umno leaders, what more does it take?" she said.