Defence Secretary Gavin Williamson will stress how the "chemical threat does not just come from Russia", as he announces a multimillion-pound investment in a new specialist centre.

After the nerve agent attack on ex-spy Sergei Skripal and his daughter and the growing possibility of further attacks, British troops will also be vaccinated against anthrax, he will reveal.

In his first keynote speech since becoming Secretary of State last year, Mr Williamson will set out the threats facing the UK, his vision for the Modernising Defence Programme, and make the case for investment in the armed forces.

"If we doubted the threat Russia poses to our citizens, we only have to look at the shocking example of their reckless attack in Salisbury," Mr Williamson is expected to say.

"We know the chemical threat doesn't just come from Russia but from others.

"But we have world-class expertise at Defence Science Technology Laboratory (DSTL) Porton Down and today I can announce we will be strengthening this capability by investing £48m in a new Chemical Weapons Defence Centre to ensure we maintain our cutting edge in chemical analysis and defence."

Experts based at DSTL in Wiltshire were tasked with analysing the nerve agent used to poison Mr Skripal and his daughter Yulia, and played a crucial role in linking the attack to Russia.

In light of what he will describe as a growing chemical, biological, radiological and nuclear threat from a range of state actors, he will confirm that thousands of British troops who are held at high-readiness will be vaccinated against anthrax.

In a move to ensure personnel are protected and ready to deploy to areas where the risk of this type of attack exists, Mr Williamson will state how the voluntary vaccination will offer "vital protection against a deadly danger".

Anthrax is a spore-producing bacterium and is often used as a weapon in a powder, spray or as an aerosol - with inhalation the most dangerous form of transmission and usually fatal.

Mr Williamson is also expected to warn how the country has "arrived at a profound moment in our history", stressing there is a "crossroads where the choice before us as a nation is simple - to sit back and let events overtake us or step forward".

"As Brexit beckons, the eyes of the world are on us. Rest assured our adversaries will be watching even more closely than our allies," he will add.

"This is our moment to retain our competitive advantage."

During his speech on Thursday, hosted by Policy Exchange and Rolls Royce in Bristol, Mr Williamson will also set out his vision for the ongoing Modernising Defence Programme.

The South Staffordshire MP will say that the programme, launched in January and due to report in the summer, will give Britain a "more productive, harder-hitting joint force", which is able to counter conventional threats and "deal with the new challenges of asymmetric conflict".

This will mean taking intelligence, surveillance and reconnaissance capability "to the next level", and "accelerating" the development of specialist Army information unit, 77 Brigade, he will add.

Amid the emerging threats facing Britain and a shortfall in the defence budget over the next decade of an amount thought to be at least £20 billion, Mr Williamson is also expected to say that the UK "must prioritise investment in military capabilities".