By Liz Hampton

DENVER- U.S. hydraulic fracturing firm Liberty Oilfield Services on Thursday warned that demand for fracking services will outpace availability, adding that it has no plans to build new frac fleets.

The second-largest fracking services company said pricing is rising, in part due to inflation, and that it still anticipates hitting mid-cycle returns this year. Access to frac sand and labor remain an issue, it said.

Shares were up almost 15% in early trading to $20.05.

Liberty emphasized to investors that it had no plans to quickly invest in building new hydraulic fracturing fleets and instead would focus on upgrading its current equipment.

"We're heading toward a better balanced market," Liberty Chief Executive Officer Chris Wright said, lamenting an oversupply of pressure pumping equipment that drove prices lower in recent years.

The current lack of equipment and rising demand from U.S. oil and gas producers echoed comments earlier this week by oilfield rival Halliburton. Its CEO said its fracking fleet was sold out and the rest of the market appeared to be fully booked for the second half of the year.

There is now more competition for frac fleets and not every oil producer that wants to secure services will be able, Wright said.

Consultancy Primary Vision estimates that the market will exit April at around 285 to 290 active frac spreads, and add another 10 in May.

(Reporting by Liz Hampton in Denver; editing by Mark Porter)