Ms Armstrong was replying to a Westminster Hall debate initiated by former Conservative environment minister Christopher Chope, MP for Christchurch, who accused the government of wanting to divide the country.
Ms Armstrong said: 'The regional policy is not just a whim of government but one that comes from a clear understanding of what is going on in the regions now. It is important to address imbalances from a regional perspective.
'It is necessary to back regional and local enterprise and initiative by exploiting indigenous strengths in regions and cities. Regional policy must be bottom-up rather than top-down, and further steps are required to deliver greater accountability and scrutiny both regionally and locally,' she said.
Mr Chope said the government's policy of regionalism was to divide the UK by imposing top-down structures.
'The model that suits Dorset and England better is one in which local communities govern themselves through a network of truly local councils.'