Armed men robbed the Punjabi Supermarket in Railway Road before setting fire to it, which caused an explosion and injured a male employee.

Hawkesbury state Liberal MP Ray Williams accused the State Government of failing to ensure adequate policing.

``Quakers Hill police station is just 50 metres from the restaurant that was robbed and blown up,'' Mr Williams said.

``Unfortunately the lack of resources meant police were unable to stop this brazen attack.''

He said the Liberal Party had already lobbied for more police at Quakers Hill.

He accused the Government of being more concerned about its internal leadership problems.

Riverstone state Labor MP John Aquilina said the Opposition was trying to make political capital out of someone's misfortune.

``I've spoken to the police and they say they have made no claim about lack of resources,'' he said.

``They've got four detectives working on this case.

``The police also said the store could have been five metres away but there was nothing they could have done to prevent the crime because they had no warning.''

Mr Aquilina said he would be speaking to the owner of the supermarket.