People who bite, spit or expose police and other frontline emergency workers to the risk of contracting a disease will be forced to undergo a blood test as part of tough new laws.

The new scheme will give New South Wales authorities powers to test a person for communicable diseases such as HIV, Hepatitis B or Hepatitis C almost immediately.

Previously, emergency workers exposed to injuries carrying the risk of contracting the disease would have to wait months for rigorous testing to come back.