BILLINGS, Mont. -

The Latest on a petition to require companies to divulge more information about chemicals pumped underground during fracking for oil and gas. (all times local):
   
3:30 p.m.
   
Montana regulators have turned back an effort to make energy companies divulge more information about fracking chemicals that are used to produce oil and gas.
   
Thursday's action leaves in place a 2011 state rule that allows companies to conceal the ingredients of some chemicals that are considered trade secrets.
   
The Montana Oil and Gas Conservation Board voted unanimously against a petition that would have made companies either disclose details on the chemicals or else justify withholding them.
   
During fracking, companies pump large volumes of industrial fluids underground to release oil and gas trapped in rock formations.
   
A group of landowners, environmentalists and health advocates say harmful chemicals in those fluids can threaten water supplies. They argued the current state rule violates the public's right to know about matters that can threaten public health.
 
9 a.m.
   
Montana regulators are to consider a petition that would force companies to divulge more information about fracking chemicals they use to produce oil and gas.
   
A 2011 state rule allows companies to conceal chemicals considered trade secrets.
   
They say it violates the public's right to know about chemicals that threaten public health.
   
The group petitioned the Montana Oil and Gas Conservation Board in July to tighten its rules.
   
Board administrator Jim Halvorson says a decision is expected following a public hearing Thursday in Billings.
   
The Montana Petroleum Association has said the public should not have access to proprietary company information.
   
During fracking, companies pump millions of gallons of fluid underground, to release oil and gas trapped in rock formations.