That reverses existing plans to reduce the stockpile to 180 by the middle of the decade, and a longstanding policy of gradual nuclear disarmament.
The 100-page document - entitled Global Britain in a Competitive Age - argues the increase in nuclear warheads cap is "in recognition of the evolving security environment" and the "developing range of technological and doctrinal threats", the Guardian said.
"While the United Kingdom cites increased security threats as justification for this move, the appropriate response to these challenges should be to work multilaterally to strengthen global arms control agreements and to reduce - not increase - the number of nuclear weapons in existence", said Mary Robinson, chair of the group.
PM Johnson's government said it would "tilt" its focus towards the Indo-Pacific region as part of its Integrated Review of government policy for the coming years, saying the area increasingly represented the geopolitical centre of the world. To be open, we must also be secure.
This would be Johnson's first major worldwide trip after Britain's exit from the European Union. The potential deployment of Queen Elizabeth aircraft carrier's is also expected to raise military tensions in the South China Sea.
In its security and defence review, Britain said it faced risks from nuclear-armed states, emerging nuclear states and state-sponsored nuclear terrorism, and its nuclear deterrent was needed to guarantee its security and that of its allies.
It is also said to include a personal commitment from the Prime Minister to to restore foreign aid spending to 0.7% of national income "when the fiscal situation allows" following furious criticism of cuts to support for Yemen and other countries.
"If "Global Britain" is to mean anything, it can not mean selling arms to Saudi Arabia and cutting aid to Yemen", Starmer said. Julian Lewis, who chairs the parliamentary Intelligence and Security Committee, described the British government's stance as one of "grasping naivety". Instead of confrontation, Britain is likely to seek to engage with Asian powers like India to work out a united strategy to deal with Beijing. The new priorities are the result of a year-long review of Britain's security, defense, worldwide development and foreign policy.
The publication comes after the Prime Minister announced in November a £16.5 billion increase in defence spending over the next four years focusing on the future battlefields of space and cyber.