© The Associated PressFranken (left), Schumer, Whitehouse and Blumenthal wrote to Facebook about privacy.

Democrats on the Senate's newest privacy panel are urging Facebook to "reverse" a plan that would allow app developers the ability to request access to users' addresses, phone numbers and other contact information.

It's the strongest signal of concern yet coming from Capitol Hill, where other members have questioned Facebook's new feature since the social network disabled it amid controversy in January.

This time, the letter is from Sens. Al Franken (D-Minn.), Chuck Schumer (D-N.Y.), Sheldon Whitehouse (D-R.I.) and Richard Blumenthal (D-Conn.). The lawmakers stress that access to a user's contact information threatens a person's other sensitive data - including his or her e-mail address and family members' names.

The members are calling on Facebook to "reconsider this policy," or at least "block this feature for Facebook users between 13 and 17 years of age."

Franken and his colleagues are also asking Facebook to disclose to users clearly how this information can be abused. They would like to require - if "operationally possible" - that all apps still be available to users who decline to grant apps access to their contact information.

"The changes Facebook is contemplating would allow countless application developers to access a vast repository of personal information with just one or two clicks from a user's mouse," wrote Democrats on the Senate Judiciary Committee's new privacy panel, which Franken chairs.

"In our opinion, the risks presented by these changes are too high - especially for thirteen- or fourteen-year-olds who may have no conception of the consequences for disclosing this kind of information," they continued.

A spokesman for Facebook said Wednesday that the company "appreciate[s] all of the feedback we're getting on this issue, and that feedback will inform the decisions we make as we continue to develop the feature."

"We believe there is great value in letting people choose to share information about themselves on Facebook, just as they are voluntarily registering this information on sites across the Web, and offline in ways as simple as a return address sticker," the spokesman continued.

"Despite rumors, apps and external websites cannot access a user's address or phone number from Facebook without that user's permission. People are always in control of what information they share through our service," the spokesman said.

Still, Capitol Hill has cast a critical eye on Facebook's plans since controversy caused the social network to suspend them in January.

For its part, Facebook has said publicly it thought the feature would, for example, help deliver coupons to mobile phones via the social network. It has repeatedly pointed out that it isn't turning over addresses and phone numbers to developers but, rather, is granting them the opportunity to ask users to share that information.

But Reps. Joe Barton (R-Texas) and Ed Markey (D-Mass.), the co-chairmen of the House's Bipartisan Privacy Caucus, still fired off a letter in February expressing concern that Facebook's new policy threatened the privacy of its users - particularly teens.

Facebook replied in late February that the company was still weighing whether to allow third parties to request access to users' addresses, phone numbers and other contact details. But the company also suggested that any attempt to restore the feature could arrive with new warnings designed to inform users more clearly what they're sharing. The company also suggested it was "actively considering whether to enable applications to request contact information from minors at all."

Those are the same sorts of changes Franken, Schumer, Whitehouse and Blumenthal requested on Wednesday "at minimum" - although they did also urge Facebook in their letter to nix the feature entirely.

By the members' reasoning, malicious actors can easily take those shared addresses and phone numbers and use them to obtain other records about a Facebook user.

"Anyone with ten minutes, 25 dollars and a Facebook user's phone number and address and no other information can obtain a breathtaking amount of information about that Facebook user - and that Facebook user's family, friends, neighbors and landlord," they wrote. "Combined with a targeted Google search, these two pieces of information can allow someone to obtain almost all of the information necessary to complete a loan or credit card application. It is hard to contemplate all the different ways in which this information could be abused."