Four police officers arrived after Dr Singer attempted to enter the DoH's Whitehall HQ and deliver a statement to health secretary Andrew Lansley.
Earlier Dr Singer and representatives from campaign group Keep Our NHS Public spoke in front of Richmond House with a banner reading: 'They lied about health too. Keep our NHS public.'
The group feel increasing competition in the NHS will lead to the closure of NHS hospitals and private sector dominance. The campaigners have attracted a petition of over 400 signatures against the recent Health Bill.
'GPs' power will be swept away by the NHS Commissioning Board,' warned Dr Singer. 'This change will pit patients against GPs. They will not know if they are acting in their best interest or the interest of the consortia,' he said.
Dr Singer said he was concerned 'that GPs will be used to build up consortia and it will be easy for the private sector to move to a dominant role'.
Former Labour health secretary Frank Dobson and MP Jeremy Corbyn (Islington North) were present and offered their support to the protesters.
Dr Singer was prevented from entering the building by police
The scuffle prevented DoH staff from getting in and out of the building for about five minutes. Eventually Dr Singer was let in and after about 20 minutes inside, he left after Mr Lansley's diary secretary agreed to take the statement and petition.
Dr Singer outside Richmond House with the letter for Mr Lansley