Abuja — Nigeria' oil giants the Royal Dutch Shell PLC and Chevron Corp will soon renew oil leases with the Nigerian government despite uncertainty caused by the absence of President Umaru Yar'Adua due to ill health, Special Adviser to the President on Petroleum Matters, Emmanuel Egbogah has said.

"Shell and Chevron have some outstanding issues they're trying to resolve, but definitely the renewal is sure," Egbogah, said in an interview with Dow Jones Newswires. "We're quite confident that there's not going to be a problem of non-renewal."

Egbogah would not elaborate on the specific issues holding the renewals up, but said "they are not serious," according to Dow Jones.

Nigerian President Umaru Yar'Adua has been in Saudi Arabia receiving medical treatment since Nov. 23, but his absence has not affected renewal negotiations, Egbogah said.

Either way, "the president will be home soon," said Egbogah.

ExxonMobil Corp. signed a renewal deal for leases of four oil fields in December 2009, for 20 years with an option to renew.

Meanwhile, Shell says it plans to continue record spending this year in its search for oil and gas. The oil giant had said it would spend $32 billion in 2010.

"We need to keep investing throughout the cycle," Chief Executive Officer Peter Vosser said at the World Economic Forum's annual meeting in Davos, Switzerland, Thursday..

Voser, who took over from Jeroen van der Veer in July, inherited the industry's biggest spending programme in 2009, amounting to $32 billion, in the middle of a global economic crisis that forced oil companies to delay some projects and cancel others.

Shell aims to increase production from existing reserves through 2020 by starting new projects that can pump more than 1 million barrels a day.