WASHINGTON, Jan. 17 -- U.S. President Barack Obama on Friday offered a series of changes to the National Security Agency (NSA)'s controversial surveillance practices, seven months following the controversy around the world sparked by formal defense contractor Edward Snowden's disclosures of the secret surveillance programs.

Speaking at the Justice Department, Obama outlined his plan to pull back some of the NSA's surveillance programs while defending the secret surveillance as a whole in the post 9/11 period.

As for domestic surveillance, Obama said he was seeking to alter the bulk collection of U.S. citizens' phone records, known as Section 215 of the USA Patriot Act.

"I am therefore ordering a transition that will end the Section 215 bulk metadata program as it currently exists, and holding this bulk metadata," said the president.

Obama has been carefully evaluating for weeks the 46 recommendations brought up by an outside advisory group appointed by himself.

According to the report releases last month by the White House, the panel called for "a series of significant reforms" to enhance transparency and privacy to the controversial NSA surveillance programs. Among them, the panel suggested that the government's current bulk storage of telephone metadata should instead be held either by private providers or by a private third party.

"This will not be simple," Obama said in his address, adding that both options will pose "difficult problems."

He directed Attorney General Eric Holder and the intelligence community to develop options for a new approach of the program without the government holding the metadata and report back to him before March 28.

However, some of the president's proposed reforms will require action and approval by Congress. Obama said he will consult with relevant committees in Congress, and seek congressional authorization for the new approach as needed.

To respond to the privacy woes, Obama also asked Congress to approve the establishment of a panel of advocates who can represent privacy interest before the Foreign Intelligence Surveillance Court, the special court that reviews and greenlights the surveillance practices.

Obama's announcement of new proposals to reform the surveillance programs is also aimed at foreign audience. Media exposures last year showed the U.S. intelligence agencies have been spying on foreign countries, including the public and leaders of America's European allies. The revelation further stirred up anger and criticism against U.S. surveillance around the world.

In his address, Obama vowed that the U.S. will only use those intelligence for "legitimate national security purposes," and not for "the purpose of indiscriminately reviewing the emails or phone calls of ordinary people."

"Given the understandable attention that this issue has received, I have made clear to the intelligence community that -- unless there is a compelling national security purpose, we will not monitor the communications of heads of state and government of our close friends and allies."

Leaders of the U.S. allies, as he put, should feel confident that "we are treating them as real partners."

However, Obama also stressed that the U.S. intelligence agencies will continue to gather information about intentions of foreign governments.

"We will not apologize simply because our services may be more effective," he added.

The president's much-anticipated move is aimed to calm the furor and controversy at home and abroad following leaks by Snowden since June. But the major part of his remarks appeared primarily designed to reassure the public about the U.S. intelligence surveillance.

The president made it clear that the NSA's surveillance programs remain as critical tools for U.S. intelligence agencies to prevent and combat terrorism, and serve the national security interests.

"What I did not do is stop these programs wholesale -- not only because I felt that they made us more secure, but also because nothing in the initial review, and nothing that I have learned since, indicated that our intelligence community has sought to violate the law or is cavalier about the civil liberties of their fellow citizens," he said.

Obama also criticized Snowden's "sensational" way of disclosures that has often "shed more heat than light."