* Shell upstream boss Brown sees 'no merit' in tax claim
* Bonga Southwest development decisions may slip into 2020
* Shell to fast track Whale development in Gulf of Mexico
By Ron Bousso
LONDON, Feb 26 (Reuters) - Royal Dutch Shell saidon Tuesday that Nigeria's claims that it was owed billions intaxes could delay the development of a major oil field off thecoast of the West African nation.
Nigeria ordered several major foreign oil and gas companiesto pay nearly $20 billion in taxes it says are owed to localstates, industry and government sources toldReuters.
Shell, the largest investor in the West African nation,would likely dispute the charges, Shell's head of upstream AndyBrown told Reuters on the sidelines of the InternationalPetroleum Week conference.
"It is something that has gone through the courts in Nigeriawhich relates to an original clause within the original PSCs(production sharing contracts)," he said in an interview.
"We will have to take it seriously but we think it has nomerits," said Brown, who steps down from his role this year.
The outstanding tax issue will delay the final investmentdecision (FID) on developing Shell's Bonga Southwest deepwateroil field, one of Nigeria's largest with production expected toreach 180,000 barrels per day, Brown said.
"We'll need to resolve that before we ever FID the BongaSouthwest project," he said.
Shell has made progress with the government on some basicterms for operating the field but a decision on its developmentwas now unlikely to be made in 2019. "Bonga Shouthwest's FID mayslip into next year." Brown said.
In the Gulf of Mexico, Brown said Shell planned to moveswiftly to develop the Whale discovery, which it announced inJanuary 2018. Shell holds a 60 percent stake in the field andChevron the remaining 40 percent.
"We're going to crack on with the development of thisproject," he said, without giving a specific timeline for thedevelopment except to say it would be "fast".
He said the field had the potential to be developed into anew production hub for Shell in the Gulf of Mexico.
Shell and many of its peers have been cutting costs sharplyfor developing large offshore fields to compete with cheapersources of oil such, as U.S. shale.
(Reporting by Ron BoussoEditing by Edmund Blair)
