Published: Oct 26, 2012 3:34 PM EDT
Updated: Oct 27, 2012 6:31 AM EDT

SAN FRANCISCO (AP) - Former U.S. Sen. George Mitchell is stepping down from overseeing private settlement talks over the deadly San Bruno pipeline explosion.

The California Public Utilities Commission appointed the former Senate Majority Leader earlier this month to mediate a settlement regarding whether Pacific Gas & Electric Co. should be fined for the blast.

But the cities of San Bruno and San Francisco as well as the commission's own consumer advocacy branch called the mediation process an unfair, backroom deal after they received word that PG&E had gotten advance notice of Mitchell's hiring.

Neither PG&E nor Mitchell's law firm immediately returned emails and voicemails seeking comment Friday. Commission staff said in an internal letter that settlement talks could restart Monday without a mediator.

The 2010 blast killed eight people and destroyed 38 homes.