Deputy Prime Minister Najib Abdul Razak on Tuesday pledged to crack down on crime in Johor and not to "flip-flop" on foreign investment policy as it pursues plans to turn the sleepy state into a modern business hub.

Najib, speaking after closed-door meetings with potential investors for the Iskandar Development Region (IDR) project in Johor, said crime in the southern state had been among their chief concerns.

"The police know the importance of the Iskandar Development Region," Najib said at a media briefing.

"They will undertake a proper plan on how to combat crime and I will convey these concerns to the police.

"I will talk to them and see what they are likely to do to ensure a safe and secure environment."

Malaysia has long dreamed of turning Johor into a major metropolis to rival gleaming Singapore, which it neighbours. But the shabby state capital Johor Baru has struggled to shrug off a reputation for crime and disorder.

The country is aiming to attract RM50 billion to the IDR in the next five years.

The planned business hub will be 2.5 times the size of Singapore and cover an area of 2,217 square kilometers.

No flip-flop policies

Najib said potential investors were also assured there will be no "flip-flop" by Malaysia in its drive to draw more foreign investment into the country.

"Policies will be consistent... I gave the assurance to them that a development like the IDR is a concept development which has the support of not only the prime minster but the entire cabinet," said the deputy prime minister.

"We will not flip-flop and neither will we lose focus because we realise that we are living in a different world," he said.

Singapore, the wealthiest economy in Southeast Asia, is among the countries being wooed to invest in the IDR project.

Najib said the meetings with potential investors in Singapore have been very encouraging.

"I have been most encouraged by the sessions we had today," said Najib.

"Overall I am very pleased that we have been able to engage with the fund managers and hopefully we will see some positive results arising out of these meetings with them," he said.

Najib said the size of investments committed to the IDR project will be made public in the second half of the year.