Tonga's Prime Minister Akilisi Pohiva made the offer while in London for the Commonwealth Heads of Government Meeting.
He and other Pacific leaders had talks with the head of Britain's Diplomatic Service at the Foreign and Commonwealth Office, Sir Simon McDonald, at a Ministerial Roundtable meeting.
Sir Simon said his government would soon announce plans to re-engage with the South Pacific which would include re-opening missions in some Island states.
The move comes as the UK prepares to exit from the European Union within 12 months.
