DALLAS — A dozen environmental and liberal-advocacy groups organized protests against Exxon Mobil Corp. on Tuesday to object to the oil giant's effort to expand oil drilling in Alaska and to cast doubt on the science of global warming.

The groups held a series of news conferences and launched a Web site to ask consumers and investors to boycott Exxon Mobil, the world's largest publicly traded oil company.

The groups, which include the Sierra Club, Greenpeace and MoveOn.org, said Exxon put profits ahead of a clean environment.

They said Exxon contributed more than $15 million over six years to groups that challenge widespread beliefs about global warming. They also complained about Exxon's lobbying to open the Arctic National Wildlife Refuge in Alaska to oil drilling and its appeals against a $4.5 billion verdict stemming from the 1989 Exxon Valdez oil spill.

"On arctic drilling and global warming, they are the worst of the worst," said Athan Manuel, an official with the environmental group U.S. PIRG.

The groups want Exxon to support mandatory limits on greenhouse emissions and invest more in renewable energy.

Exxon spokesman Russ Roberts said the company recognized the risk of climate change and had invested in technology that could reduce emissions of greenhouse gases, including plans to invest $100 million over 10 years in climate research.

On drilling in Alaska, Roberts said Exxon "supports environmentally responsible development" within a portion of the Arctic refuge.

"We believe that with more than 30 years of industry experience on Alaska's North Slope and with recent technological advancements, ANWR can be developed with little threat to the ecology of the Coastal Plain," he said.

Protest organizers said they held demonstrations in more than 50 cities around the country.

Exxon Mobil is no stranger to protests. Its annual shareholder meeting in Dallas regularly draws dozens of environmental and human-rights protesters, although they skipped the event this year.

The company was the target of a one-day boycott in 1989 after the Exxon Valdez spill, and a longer protest in Europe in 2001 over its opposition to the Kyoto Protocol, an international treaty on global warming.

Exxon Mobil's 2004 profit -- more than $25 billion -- is believed to be a record, excluding one-time gains from selling a business, by a U.S. corporation. Irving, Texas-based Exxon Mobil had sales of $298 billion.

Source: Associated Press