Britain's Defence Secretary Gavin Williamson has accused Russia of spying on its critical infrastructure as part of possible plans to create ‘total chaos’ in the country that could ‘cause thousands and thousands of deaths’.

Williamson said that, in its research on UK power supply connections with Europe, Moscow appeared intent on sowing ‘panic’ and hurting Britain.

He said: ‘What they are looking at doing is they are going to be thinking 'how can we just cause so much pain to Britain?’ Damage its economy, rip its infrastructure apart, actually cause thousands and thousands and thousands of deaths, but actually have an element of creating total chaos within the country.’

Williamson, who only became defence chief in November 2017 after predecessor Michael Fallon resigned over allegations of misconduct, is reportedly pressuring Finance Minister Philip Hammond to allocate more money to defence and scrap further cuts to Britain's strained armed forces.

The minister said Russia acts in a way ‘that any other nation would see as completely unacceptable’.

Williamson added: ‘Why would they keep photographing and looking at power stations, why are they looking at the interconnectors that bring so much electricity and so much energy into our country.

‘They are looking at these things because they are saying these are the ways that we can hurt Britain.’

Earlier this week Fallon joined calls from the head of the army for more British military spending, amid warnings the country may struggle to match Russian battlefield capabilities.

Meanwhile the head of the National Cyber Security Centre said the country will likely face a major cyber-attack within two years.

Ciaran Martin said it was inevitable a hostile actor would launch an online attack aimed at crippling Britain's critical infrastructure, such as energy supplies, and it was lucky not to have fallen victim to such a strike already.

Williamson, who is tipped as a possible future ruling Conservative party leader, described his scenario planning as ‘the real threat that I believe the country is facing at the moment.’