SAN BRUNO -- City officials in San Bruno on Tuesday demand the release of key internal documents and emails of the state Public Utilities Commission in connection with the decision making process leading to proposed penalties for PG&E because of a fatal natural gas explosion and disaster in 2010.

Municipal officials also demanded that the documents and emails be turned over to the city by the end of the day on Friday. If San Bruno doesn't receive the requested information, the city intends to take further legal action.

The demands were a fresh twist in the furor over the proposal by the PUC staff to punish PG&E in such a fashion that the utility wouldn't have to pay an outright fine in connection with the natural gas explosion that killed eight in San Bruno. They come on the heels of the disclosure of internal PUC emails that suggest, according to critics of the commission, that PUC attorneys were subject to intimidation during the decision-making process for the proposal.

"The latest revelations add to a long list of possible illegal activity at the PUC," San Bruno Mayor Jim Ruane said. "The integrity of the PUC is at stake, as is the safety of every Californian."

Earlier this month, San Bruno called upon the state's Attorney General and state lawmakers to investigate the re-assignment of top attorneys with the PUC's safety division. The attorneys were handling the PUC's probe into the PG&E natural gas explosion.

The attorneys refused to endorse a recommendation by Jack Hagan, the head of the PUC safety division, that PG&E pay $2.25 billion in repairs and improvements to the natural gas system -- but not pay a fine as punishment for causing the explosion.

San Bruno officials also demanded that the PUC not destroy any documents or emails and instead make all the records in the matter public immediately.

"I'm grateful to San Bruno for dong this," said state Sen. Jerry Hill, D-San Bruno. "We have been trying to initiate audits and every type of investigation we can think of, but the politics at the PUC and the influence of the utilities stymie what we are trying to do."

Officials at the PUC didn't provide an immediate comment about the San Bruno demands.

"The City of San Bruno is seeking justice for PG&E's decades of mismanagement and yet the CPUC's top staff and PG&E continue to play Russian roulette with the lives of Californians," Mayor Ruane said. "We ask for full transparency so that some semblance of integrity can be restored in this process."

The PUC staff, and parties in the penalty case against PG&E, including the city of San Bruno, have submitted briefs in the matter. Those documents are part of a review by PUC administrative law judges. These hearing officers will issue this year a proposed ruling about the penalties. It's expected that by year's end, the five-member commission that heads the PUC will make a final decision on the matter.

Sen. Hill said wholesale changes are needed at the PUC to usher in an improved system at the state agency. That includes the ouster of PUC president Michael Peevey, Hill said, The five PUC commissioners, including Peevey, are appointed by the governor.

"There has been no credibility or integrity at the PUC for the last two years," Hill said. "Safety is still not a priority at the PUC. The only one who can make the necessary changes is the governor."

Contact George Avalos at 408-373-3556 or 925-977-8477. Follow him at twitter.com/george_avalos.