A billboard shows portraits of Prince Mohammed bin Salman and Imran Khan in Islamabad. (AFP)

Saudi Arabia's Crown Prince Mohammed bin Salman is due to arrive in Pakistan today at the start of his tour of South Asia and China, but the visit risks being overshadowed by escalating tensions between India and Pakistan.

The trip comes days over 40 Central Reserve Police Force (CRPF) were killed in a car bomb attack in Jammu and Kashmir's Pulwama. New Delhi has accused Pakistan of having a hand in the bombing and vowed to punish Islamabad, which denies involvement.

The attack has been claimed by Pakistan-based terror group Jaish-e-Mohammed, whose chief Masood Azhar roams freely in Pakistan.

New Delhi is demanding Islamabad act against the Jaish-e-Mohammed (JeM).

Cash-strapped and in need of friends, Pakistan is welcoming the crown prince with open arms for a visit during which he is expected to sign investment agreements worth more than $10 billion.

Saudi Arabia has in recent months helped keep Pakistan's economy afloat by propping up its rapidly dwindling foreign exchange reserves with a $6 billion loan, giving Islamabad breathing room as it negotiates a bailout with the International Monetary Fund.

Analyst say the crown prince's trip is being treated by Islamabad as the biggest state visit since Chinese President Xi Jinping in 2015, soon after Beijing announced plans to invest tens of billions of dollars on infrastructure in Pakistan as part of China's global Belt and Road initiative.

The visit marks a deepening in ties between allies whose relationship has in the past centred on oil-rich Saudi Arabia backing Pakistan's economy during difficult periods, and in return Pakistan's army lending support to Saudi Arabia and its royal family.

As the guardians of most holy sites in the birthplace of Islam, the Saudi royal family carries vast religious clout in Pakistan.

"What is happening in this relationship is a renewal of Pakistan's commitment to help protect the royal family and the order as it exists in Saudi Arabia," said Mosharraf Zaidi, Senior Fellow at Tabadlab, a Pakistani think tank focused on global and local public policy.

"On the flip side, there is reassurance that Saudi Arabia will not only continue to serve as a strategic friend who will help shore up Pakistan's finances when needed, but it's also going to become a participant in the wider investment in Pakistan."

Pakistan is shutting down its airspace and has stepped up security in Islamabad for the crown prince, who is set to become the first guest to stay at the prime minister's House. Pakistan's new populist premier, Imran Khan, has refused to use the residence in a bid to save taxpayers' money.

Pakistani hopes for further investment opportunities from Saudi Arabia were dealt a blow on Saturday when the government announced that the Pak-Saudi Business Conference had been "postponed".

Pakistani officials have already flagged up that Saudi Arabia will announce eight investment agreements, including a $10 billion refinery and petrochemicals complex in the coastal city of Gwadar, where China is building a port.

But the crown prince's arrival comes after steps taken by India to isolate Pakistan internationally following the deadliest attack on security forces in Jammu and Kashmir in decades.

In Islamabad, the crown prince is expected to meet Imran Khan and Pakistan's army chief, Qamar Javed Bajwa. He is also likely to meet representatives of the Afghan Taliban to discuss peace negotiations to end the 17-year civil war in Afghanistan, Pakistani government sources say.