The Financial Times said the prime minister is keen to focus on new measures to protect the country from evolving threats like extremism, cyber warfare and the dangers posed by increasing aggression from Russia.

"As prime minister, I will always put the national security of our country first. That's why it is right that we spend 2% of our GDP on defence, because this investment helps to keep us safe," Cameron said.

"Now we know how much we will spend, what matters next is how we spend it. I have tasked the defence and security chiefs to look specifically at how we do more to counter the threat posed [Isis] and Islamist extremism," he said, according to the Financial Times.

This, he added, could "include more spy planes, drones and special forces. In the last five years, I have seen just how vital these assets are in keeping us safe," he added.

On Monday Mr Cameron will visit RAF Waddington, the UK’s drone base in Lincolnshire, which co-ordinates flights of unmanned aircraft over Iraq and Syria. The UK is part of a coalition of more than 60 countries opposing Isis, but while in Iraq the RAF’s jets and drones are carrying out attacks on Islamic militants, in Syria drones are limited to a surveillance role. Ministers are attempting to build a consensus to extend the RAF’s air campaign to include strikes against Isis targets in Syria.

The RAF’s jets and drones are part of the coalition attacking IS in Iraq, but in Syria the drones are limited to a surveillance role – although ministers have begun setting out the case to extend the bombing campaign to the terror group’s strongholds in that country.