Saudi Arabia's National Commercial Bank (NCB) has invited banks to pitch for the adviser role on its highly-anticipated flotation on the kingdom's bourse, said the kingdom's top lender.

The Saudi government said last month it planned to sell a 15 per cent stake in the kingdom's largest lender to the public this year, a long-awaited move which is likely to result in one of the biggest initial public offerings (IPOs) ever seen in the Gulf region.

For investment banks in the kingdom, the share sale is a must-have mandate to be working on and they were invited by NCB to pitch for the adviser role on the transaction earlier this week, banking sources said.

"A request for proposals (RFP) was sent to a select number of authorized persons to act as the financial advisor for the IPO process as per Capital Market Authority requirements," said NCB in a statement, referring to the Saudi regulator.

"Once the selection is made, the selected financial advisor will be announced."

A decision on which bank will work on the IPO is expected soon, given that the government wants to sell the stake before the year end, said one banker who has seen the RFP.

Another banker, while declining to specify the timetable for NCB, said a decision on RFPs in Saudi was usually made around two to three weeks after they are sent out.

Given the substantial size of the share sale - estimates by bankers put it in the region of 15 billion to 20 billion riyals ($4 billion-$5.33 billion) - and the fact all Saudi share offerings must be underwritten before being sold to the public, a number of banks are expected to be ultimately involved.

When Saudi Arabian Mining Co (Ma'aden) did its 9.2 billion-riyal IPO in 2008, all 11 Saudi lenders were involved in some form of underwriting capacity.

However, on the NCB deal, the title of financial adviser will be the most coveted, given both the prestige of the mandate and the fees to be generated.

Every bank with advisory capabilities in the kingdom will likely pitch therefore, including Saudi banks and the Saudi units of international banks like HSBC, JP Morgan and BNP Paribas.-Reuters