Two of the world's biggest hotel chains are facing public pressure to sever their affiliation with the National Rifle Association in the wake of the school shootings in Newtown, Connecticut.

Avaaz, a global campaign network of 17 million people, is targeting Wyndham Hotels Worldwide – which owns Ramada, Days Inn, Wingate and Super 8 – and Best Western. Both are listed on the gun rights group's website under the heading "friends of the NRA" because they offer members discounts through its business affiliates programme.

Both hotel chains' Facebook pages are full of messages urging them to "get out of bed with the NRA", many of them threatening to stop using their hotels until they do.

At least 66,000 people have also signed up to a petition organised by Avaaz, calling on the NRA to stop blocking legislation that would regulate gun ownership.

Joseph Huff-Hannon, senior campaigner at Avaaz, said: "It's time for mainstream companies like Wyndham Hotels to get out of bed with the extremist NRA. Their affiliation is a toxic approval of how this gun lobby has made America less safe for our children. The NRA's influence is already waning and the tragic events in Newtown must mark the end of the group's stranglehold on our politics."

Avaaz's action comes days after other US companies distanced themselves from gun groups.

Cerberus Capital Management LP, a private equity firm announced it would sell its stake in the group which includes Bushmaster, manufacturer of the assault rifle used by Adam Lanza to kill 20 children and six adults at Sandy Hook elementary school last Friday.

Other national retailers, such as Walmart and Dick's Sporting Goods, have suspended sales of certain weapons, including the Bushmaster rifle.

One message, written by Crissy Welch, on the Wyndham Hotels Facebook site, read: "The Connecticut shooting killed 28 poor souls, but my hometown of Flint has already seen SIXTY-FIVE HOMICIDES this year alone. This is not an isolated incidence. Wyndham Hotels, why are you in bed with the NRA? Until you pull your hotels from affiliation with the gun lobby, I will not set foot in any of your hotels or motels, and I'll tell all my friends and family to do the same."

Messages to the Best Western Facebook site included one from Patrick Ryan, which said: "Is Best Western a violent organization? Apparently, it is. It supports the widespread use of guns by supporting the NRA and their profit motive to get MORE GUNS in the hands of Americans and in their home- where they are then used to cause more harm than good. THAT, is Best Western today, no way around it. What will Best Western be tomorrow? Bankrupt or a healthy entity supporting the betterment of our lives? Decisions, decisions …"

The NRA said this week that it was willing to make "meaningful contributions" to the debate to prevent mass shootings such as Sandy Hook happening in future. It will hold a press conference in Washington on Friday where it is expected to reveal

A spokesman for Wyndham Hotels said: "We are a hospitality company focused on our service promise to be responsive, be respectful and deliver great experiences to our customers, guests, partners and communities, as well as to each other. As part of our company's core values, we serve diverse individuals and organizations."

Calls to Best Western by the Guardian were not immediately returned.

Avaaz targeted Hilton Hotels in January 2011, over what it claimed was the group turning a blind eye to the sex trade. It said that the campaign had a big impact and led the chain to train over 180,000 staff in how to detect and prevent sex trafficking.