WASHINGTON — The Obama administration has announced plans to to expand drilling activities in the Gulf of Mexico, even as lingering effects of the disastrous 2010 Deepwater Horizon oil spill are still felt along parts of the Texas coastline.

Interior Secretary Ken Salazar said the new program opens up the vast majority of known offshore oil and gas resources for development. But he acknowledged that many resource-rich areas overlap with environmentally fragile ecosystems.

“We are going to go ahead and proceed,” Salazar said, noting that he was confident that companies will implement rigorous safety standards.

Under the plan, all areas in the Gulf with the highest-known resource potential will be available for oil and gas development. The proposed program will schedule 15 potential lease sales between 2012 and 2017, including 12 in the Gulf of Mexico.

The scheduled lease sales in the Gulf of Mexico will occur in the western and central Gulf, and in the portion of the eastern Gulf not currently under congressional moratorium. The estimated undiscovered resources in these areas amounts to roughly 43 billion barrels.

Earlier this month, the Interior Department held the first sale of oil and gas leases in the central Gulf of Mexico since the BP oil spill. Interested companies submitted $1.74 billion in winning bids on nearly 39 million acres. The administration’s opening up of new energy resources came amid intensified GOP criticism of the president’s energy policies.

Environmental groups are raising concerns about the increasing enthusiasm among oil companies and the Interior Department for drilling in the Gulf of Mexico following the BP oil spill, which killed 11 people and left crude oil flowing unabated for three months. Elgie Holstein, senior director for strategic planning at the Environmental Defense Fund, an environmental group involved in coastal restoration in Texas, said it might be years before people fully understand the spill’s impact on marine life.

“We do know in Texas the shoreline didn’t experience as much damage as it did in Louisiana,” Holstein said. “I don’t think that is cause to assume there is no impact in Texas.”

BP said in an online statement that it is committed to working in the Gulf of Mexico, and that its drilling standards go beyond U.S. regulatory requirements.