Petronas has invested about US$8 billion (RM25.6 billion) in oil and gas (O&G) exploration works in Turkmenistan to further increase its production, said Prime Minister Datuk Seri Najib Tun Razak.

He said with this large investment, the involvement of Petronas in the Central Asian nation which is rich in O&G, will become more strategic in the future.

"Petronas also plans to increase its gas and petrochemical flow ( in the exploration area).

"With this, the output in the production sharing contract area can be further enhanced," Najib told the Malaysian media at the Ashgabat International Airport before leaving for home Tuesday night.

Prime Minister said apart from the Petronas investment being a pioneering cooperation between Malaysia and Turkmenistan, the national O&G company has also proven its capability in gaining recognition from the country.

According to Najib, Turkmenistan President Gurbanguly Berdimuhamedov considers Petronas as a partner which really understands the aspirations of his country.

"That is the reason why he wants Petronas to expand its investment in Turkmenistan while training the country's citizens to gain experience in the oil and gas sector," he said.

At present, Petronas is the only Malaysian company to participate in the O&G industry in Turkmenistan, through exploration works in the Caspian Sea since 1996.

Petronas entered into the production sharing contract with Turkmenistan, whereby, the Malaysian company undertakes exploration activities, before selling any oil and gas through Turkmen Gas.

On Tuesday, Petronas signed a memorandum of understanding on Long-term Cooperation between it and Turkmenistan's State Agency in Charge of Hydrocarbon.

Turkmenistan is ranked fourth among countries with proven gas reserves after Iran, Russia and Qatar, with an area of 17.5 trillion cubic metres.

Asked if other Malaysian companies have an opportunity to enter the O&G industry in Turkmenistan, the Prime Minister said the government was opening up opportunities, but priority would be given to Petronas.

Najib said the government was also encouraging Malaysian companies to explore new investment opportunities in the construction, mining, education, science and technology, halal products and Islamic banking, as Turkmenistan is now aggressively following through on its development projects.

"The Turkmenistan President is keen that Malaysia becomes a partner in all areas. This is because his confidence in Malaysia is very high.

"Malaysia has become a priority nation for Turkmenistan," he said.

Najib also considered his two-day official visit to the country as being more comprehensive compared to the inaugural trip in 2011, when the focus was more on launching the Petronas gas platform in the country.

He said Ashgabat was increasingly developing with the construction of new buildings since his visit three years ago.

"The progress in Turkmenistan is very vibrant and the economy is continuing to expand at a high level," he said.

Najib said Malaysia and Turkmenistan had agreed to establish a Joint Commission to improve further bilateral economic cooperation.

He said bilateral trade which was at US$33 million (RM105.6 million) last year did not reflect the true potential of both countries.

"As such, Berdimuhamedov wants the Commission to study ways to increase trade opportunities between Malaysia and Turkmenistan," he said.

On tourism, Najib said the government was introducing a 30-day visa free entry to encourage more visitors from Turkmenistan to Malaysia.

In 2013, only 940 tourists from Turkmenistan visited Malaysia.

Najib said Malaysia and Turkmenistan had the same standing on the international stage.

"Therefore, we will continue to work together with Turkmenistan on universal issues and matters of mutual interest," he added.

The Prime Minister was accompanied by his wife Datin Seri Rosmah Mansor on the visit.