Silicon Valley is escalating pressure on President Barack Obama to curb the U.S. government surveillance programs that vacuum personal information off the Internet and threaten the technology industry’s financial livelihood.

A coalition that includes Google, Apple, Yahoo, Facebook and Microsoft lashed out in an open letter printed Monday in major newspapers and a new website, http://reformgovernmentsurveillance.com.

The crusade united eight companies that often compete fiercely against each other, but now find themselves banding together to limit the potential damage from revelations about the National Security Agency’s snooping on Web surfers.

Twitter Inc., LinkedIn Corp. and AOL Inc. joined Google Inc., Apple Inc., Yahoo Inc., Facebook Inc. and Microsoft Corp. in the push for tighter controls over electronic espionage. The group is immersed in the lives of just about everyone who uses the Internet or a computing device.

As the companies’ services and products have become more deeply ingrained in society, they have become integral cogs in the economy. Their prosperity also provides them with the cash to pay for lobbyists and fund campaign contributions that sway public policy.

Monday’s public relations offensive is a by-product of documents leaked over the past six months by former NSA contractor Edward Snowden. The records reveal that the NSA has been obtaining emails and other personal data from major tech companies under secret court orders for the past five years and scooping up other data through unauthorized hacking into data centers.

Silicon Valley has been fighting back in the courts and in Congress as they seek reforms that would allow them to disclose more information about secret court orders. Several of the companies are also introducing more encryption technology to shield their users’ data from government spies and other prying eyes.

Monday’s letter and the new anti-snooping website represent the technology industry’s latest salvo in an attempt to counter any perception that they voluntarily give the government access to users’ email and other sensitive information.

Although the campaign is ostensibly directed at governments around the world, the U.S. is clearly the main target.

“The balance in many countries has tipped too far in favor of the state and away from the rights of the individual — rights that are enshrined in our Constitution,” the letter said. “This undermines the freedoms we all cherish. It’s time for a change.”

Civil liberties aren’t the only thing at stake. One of the reasons the technology companies have become a rich vein for crime-fighting authorities is that they routinely store vast amounts of personal data as part of their efforts to tailor services and target advertising.

By analyzing search requests, Web-surfing habits, social networking posts and even the content of emails, the companies are able to determine, for instance, the type of digital ads to show individual users. The NSA revelations have raised fears that people might shy away from some Internet services or share less information about themselves. Such a shift would make it more difficult for companies to increase their ad revenue and, ultimately, boost their stock prices.

In a statement, Yahoo CEO Marissa Mayer said the NSA disclosures had “shaken the trust of our users.”

Google CEO Larry Page and Facebook CEO Mark Zuckerberg, two of the richest people in the world, also chimed with statements urging the U.S. to adopt reforms to protect personal information.

U.S. intelligence officials have staunchly defended the electronic espionage, contending the NSA’s tactics have helped disrupt terror attacks. Officials also insist that the agency takes care not to look at the content of conversations or messages by U.S. citizens.

Obama has asked a panel of hand-picked advisers to report on the spying issue this month and recently said he’ll propose the NSA use “some self-restraint” in handling data.

White House spokeswoman Caitlin Hayden indicated the administration expects to address many of the concerns raised in Monday’s letter after Obama’s advisers complete their review. “As we have said repeatedly, we are committed to conducting intelligence activities with appropriate constraints, oversight, transparency and accountability,” she said.

Monday’s letter goes farther than the companies’ previous statements in favor of overhauling surveillance practices, according to Kevin Bankston, policy director of the New America Foundation’s Open Technology Institute. He notes that the new principles put forward by the companies include “an unambiguous condemnation” of bulk data collection as conducted by the NSA.

It was a shrewd move for the companies to disseminate the open letter through newspaper ads, said Daniel Castro, a senior analyst for the Information Technology and Innovation Foundation, a Washington, D.C. think tank.

By virtue of connecting directly with a massive proportion of the U.S. population, the companies “have a huge reach,” Castro said. “They want people to be supporting and rallying around this effort.”

The Silicon Valley companies also are waging an attack in the Foreign Intelligence Surveillance Court, where they are fighting to be allowed to reveal more details about how frequently the NSA has been seeking user data. U.S. law currently prevents the recipients of national security orders from breaking down the number of demands they get under the Patriot Act. The companies contend that restriction fuels the erroneous perception that the government has a direct pipeline to their users’ data.

The government countered with a motion on Friday arguing that it should be able to redact, or withhold from publication, parts of its justifications to the courts for barring such detailed reporting by the companies.

Technology companies are also concerned that governments outside the U.S., such as the European Union, might set tougher rules for businesses to protect the privacy of their citizens, according to Joss Wright, a research fellow of the Oxford Internet Institute.

“It’s potentially huge,” Wright said. “Other countries around the world could make it harder for (the companies) to carry on with unrestricted data gluttony.”

(AP)