Just over half a million people who still need to renew their tax credit claims are being given an extra week to do so due to strike action, HM Revenue and Customs (HMRC) has announced.

Some 550,000 people still have to renew their tax credits or risk losing their payments, and HMRC has extended the July 31 deadline to next Wednesday, August 6.

The Revenue body said it had taken the decision because people faced "long delays" trying to get through to its renewal phoneline due to industrial action taking place this week.

The phones traditionally get busier as the cut-off for renewals looms.

The Public and Commercial Services Union (PCS) is staging rolling action in various parts of the UK on Wednesday, Thursday and Friday to highlight its concerns about staff shortages.

For the first time, HMRC is offering people renewing their claims this year the option of doing so online.

They can do this either by going to the web page gov.uk/renewtaxcredits or by using the free HMRC app, which is available in the iTunes and Google Play stores.

Claimants can also renew by post or over the phone by calling 0345 300 3900.

Those renewing by phone can opt to use an automated speech-recognition service on the tax credits helpline, by saying "renewals" when prompted.

The new, extended deadline allows people to renew by any of these methods up until August 6.

The latest tally for the number of people who are yet to renew means the figure for those who end up failing to do so on time this year will come in at under the 650,000 people who missed last year's cut off point.

Tax credits are benefits that give extra money to people responsible for children, disabled workers and some other workers on lower incomes.

Some people receive child tax credits, some get working tax credits and some receive both.

Renewal packs have been sent to 5.8 million people since April and claimants have been asked to act as soon as they receive a pack.

In these packs, HMRC asks claimants to check the accuracy of the information it holds about them, and to give information about any changes to their circumstances which they have not already reported, such as to their working hours, childcare costs or pay.

A portion of these 5.8 million people do not have to do anything as their claims will automatically renew because their circumstances have not changed for some time.

But just over three million of them have needed to get in touch with HMRC to confirm their circumstances.

An HMRC spokesman said the body was " very disappointed by the timing of the decision by PCS to call a strike to coincide with the tax credits renewal deadline".

He continued: "We are giving people additional time to renew as we are determined to do everything we can to minimise the impact on tax credits claimants.

"We urge them to renew online at www.gov.uk/renewtaxcredits to avoid the long delays on the phone that will be caused by the strike."