More than 180 miles west of Barclays Bank's glistening skyscraper in the heart of Canary Wharf, a small group of tax protesters will gather outside one of its lesser-known branches.

At 10am on Saturday in Guildhall Square in Carmarthen, south-west Wales, a handful of campaigners will enter their local Barclays branch and unfurl their banner in protest against tax avoidance.

It will be one of 35 Barclays branches across the UK being occupied as part of UK Uncut, a viral protest collective set up five months ago to oppose government cuts and corporate tax avoidance.

The co-ordinated occupations of Barclays branches will mark the first national day of action against banks by UK Uncut, which has already forced the temporary closure of more than 100 high street stores.

The group has previously targeted companies such as Boots and Vodafone accused of avoiding millions of pounds in tax. Targeting Barclays has proved particularly popular, with more protests planned in large cities as well as smaller towns such as Grimsby, Hastings and Shrewsbury.

And as campaigners turn their attention to banks, and Barclays in particular, it emerged their Twitter-driven campaign has spread to the United States, where similar protests are being organised under the banner US Uncut.

"The folks in the UK who decided to stand up, organise and speak out are a daily inspiration to me and the rest of the movement in the States," said Carl Gibson, 23, one of the founders of the first US Uncut group in Jackson, Mississippi.

"The message is simple – before you sacrifice hard-working public-sector employees' jobs and necessary public programmes, why not first make the richest of the rich pay their fair share in taxes?"

Gibson, who started the first US group a week ago after reading an article in the Nation, said there were already US Uncut "chapters" in 20 states and at least 10 demonstrations planned for 26 February – the date of UK Uncut's second "day of action" against the banks.

"I'm still getting emails pouring in daily from interested citizens who want to start their own US Uncut movement in their community," said Gibson. "On 26 February … the bulk of US Uncut chapters will stage demonstrations at Bank of America locations all over. We have events planned for Seattle, Washington, Portland, Oregon, Washington DC, New York City, New York, Portland, Maine and Boston."

Protesters in the UK have mobilised thousands of activists using the Twitter hashtag #UKuncut since the group was formed in October, and Gibson says their expertise has been critical for activists in the US.

"I'm in contact with UK Uncut founders on a daily basis," said Gibson, a former radio journalist. "They've been instrumental in getting this movement off the ground here in the States. They've helped with website development, Twitter and Facebook promotion, and recruiting valuable assets with connections that can help us."

The action in the UK, which comes as banks reveal multimillion-pound bonus packages, is expected to involve a range of peaceful and creative direct actions.

In a foretaste, protesters occupied a London branch of Barclays on Tuesday, turning it into a library. The demonstration coincided with the announcement that average earnings at the bank's investment arm have risen by 23% and that CEO Bob Diamond is in line for a bonus of more than £8m.

Toni Palmer, who lives in Islington, north London, took part in the demonstration.

"The banks caused this economic crisis because of their greed and reckless gambling," she said. "But the people who are really being made to pay for it are ordinary people."

The government cuts mean Islington council is slashing its budget by £52m and cutting a range of services including police community support officers for primary schools, advice services for troubled teenagers, and help with shopping, laundry and cleaning for the elderly.

Palmer said: "Our lives are being devastated by the billion-pound cuts to essential services that we all depend on. But Barclays is paying out bonuses of £2bn. This shows that we are not 'all in this together'."