WASHINGTON — Sen. Mark Udall on Monday accused the National Security Agency of providing false information in a fact sheet about its spying programs, and in a letter to NSA director Gen. Keith Alexander, Udall said the agency is portraying stronger privacy protections for Americans than actually exist.

Udall and Oregon Democratic Sen. Ron Wyden contend the NSA’s fact sheet on the so-called 702 program, which gives the government authority to collect foreigners’ phone and Internet communications, has “significant” inaccuracies, according to the letter obtained by The Denver Post.

The fact sheet details the government’s interpretation of Section 702 of the Patriot Act, was distributed to all members of Congress and is up on NSA’s website.

The NSA’s publication maintains the government may not target any Americans anywhere in the world under this law, that there must be a “valid, documented” foreign intelligence purpose for the government to use this authority and that the government must minimize the acquisition of information that isn’t relevant to intelligence investigations.

Udall said he could not elaborate on what part of the two-page fact sheet is inaccurate because it would divulge classified information.

“In our judgment, this inaccuracy is significant, as it portrays protections for Americans’ privacy as being significantly stronger than they actually are,” the two senators wrote. “We urge you to correct this statement as soon as possible.”

The NSA did not immediately respond to The Denver Post for comment on the letter to Alexander.

“When the NSA makes inaccurate statements about government surveillance and fails to correct the public record, it can decrease public confidence in the NSA’s openness,” Udall and Wyden wrote in the letter. “Rebuilding this confidence will require a willingness to correct misstatements and a willingness to make reforms where appropriate.”

In the same letter, Udall and Wyden said the fact sheet seems to contradict earlier statements Alexander made under oath that he had no ability to determine how many American communications had been mistakenly collected by the NSA using this authority.

The fact sheet says “any inadvertently acquired communication” concerning an American must be destroyed if it isn’t relevant to any terrorism investigation.

The senators said they believe that line is “somewhat misleading in that it implies the NSA has the ability to determine how many American communications it has collected.”

Udall has been pushing Alexander to be more forthcoming on the surveillance program. In a speech last year he called it “disconcerting” that the NSA director could not give any estimate on how many Americans’ phone records and e-mails were inadvertently collected.

“It’s hard for us to believe that the director of national intelligence … cannot come up with at least a ballpark estimate,” Udall said last year

Udall introduced a law a couple of weeks ago that intends to greatly reduce the federal government’s ability to collect data on Americans’ phone calls without a demonstrated link to terrorism.

That proposal was tucked into a bigger overhaul to the Patriot Act introduced Monday.

Udall said in the letter to Alexander on Monday that he believed the U.S. government should have broad authorities to investigate terrorism and should aggressively pursue terrorists — but it should do it without compromising ordinary Americans’ constitutional rights.

“Achieving this goal depends not just on secret courts and secret congressional hearings but on informed public debate, as well,” the letter said.

Allison Sherry: 202-662-8907, asherry@denverpost.com or twitter.com/allisonsherry