LONDON (Reuters) - Britain should postpone an ongoing review of its security, defence and foreign policy for at least a year because of the widening impact of coronavirus, a leading defence think-tank said on Friday.

The government had intended to complete what is known as an "integrated review" of policy by July this year. But with time already tight and the coronavirus pandemic throwing both the British and global economy into turmoil, a delay of up to a year is needed, Britain's Royal United Services Institute said.

"The lasting consequences of the pandemic remain highly unpredictable, but are likely to include new debates on public spending priorities in the UK and elsewhere," it said in a paper co-authored by the Ministry of Defence's former director of strategy and the deputy director of RUSI.

As well as the impact of coronavirus and the not-yet complete fallout from Brexit, the authors point out that Britain's relations with the United States are in an unreliable phase and it would be better to wait until after the U.S. presidential election in November to take strategic decisions.

Russia is also an unpredictable operator, and it would be worth Britain's time to wait to see how leaving the EU while remaining a core part of NATO alters the country's defence, security and foreign policy considerations, they argue.

The growing global influence of China is another consideration, with Britain and others in Europe needing to find a more "transactional" approach to dealing with Beijing.

"If the UK wants to prosper in a difficult world, it now needs to become more focused in its approach to pursuing national interests, more able to change approach when circumstances require, and more transactional in its relationships with other states," the paper says.

The fallout from the coronavirus could also include "new geopolitical alignments between major powers, exacerbated developmental challenges in countries worst hit by the crisis and (potentially) a further strengthening of nationalist political forces."

The paper recommends pushing the review back to 2021, when the Ministry of Defence was expected to have around 39 billion pounds budgeted to it, rising to 44.4 billion pounds by 2024/5.

The full paper is available here: https://rusi.org/sites/default/files/20200324_defence_and_integrated_review_readyforweb.pdf

(Writing by Luke Baker; Editing by Daniel Wallis)