* Shell echoes concerns about changes to law
* Industry had said move would discourage investors
* Explorers interested after nearby Mozambique finds
By George Obulutsa
NAIROBI, April 30 (Reuters) - U.S. oil and gas explorerAnadarko Petroleum said it halted spending onexploration in South Africa until it has more clarity on changesin the petroleum law, which gives the state a 20 percent stakein new ventures.
South Africa's parliament passed the changes to the law lastmonth, a move industry experts said would discourage investment.
Other firms have also voiced concerns about the legislation,which gives the mines minister wide-ranging powers to placecertain minerals in a "value-addition" category, which means aportion would have to be processed domestically instead ofexported in raw form.
"We have suspended our expenditures in South Africa untilthe petroleum law and fiscal terms are more clear," TomFletcher, exploration manager for east Africa at Anadarko, toldan energy conference in Nairobi on Wednesday.
Speaking to reporters on the conference sidelines, he said:"We are just looking for a little more clarity - what's going tohappen with the fiscal regime down there - before we investlarge dollars in South Africa."
Menno de Ruig, Shell's exploration manager for newinternational upstream business in sub-Saharan Africa, echoedthose concerns at the conference.
"We are hopeful that the current uncertainty around thepetroleum bill in South Africa gets resolved in a workablemanner so that we can move forward to the drilling phase," hesaid.
The speed at which the bill passed before elections in Mayalarmed petroleum companies such as Shell, Anadarko, Total and Exxon Mobil, which want to explore SouthAfrica after making big offshore gas finds in neighbouringMozambique.
Shell has been exploring for shale gas in the onshore Karooarea, while Total said in November it expected to drill itsfirst offshore well in the Outeniqua Basin, about 175 km (110miles) off the southern coast of South Africa.
As well as the 20 percent "free carried interest", thegovernment also introduced a clause entitling it to increase itsshare of a project by acquiring a greater stake at an agreedprice or by production-sharing agreements.
Industry critics of the law say it amounts tonationalisation without appropriate compensation. (Editing by Edmund Blair and Jane Baird)