The amount of coal seam gas thought to have gushed from a well near homes at Camden last year was up to 10 times more than the figure energy company AGL later made public, government documents show, prompting claims the public was kept in the dark.

Documents obtained under freedom of information laws also revealed a series of safety issues and accidents at the company's 144-well Camden Gas Project. They include a rig manager who worked 21 days' straight and a sudden release of gas that injured workers.

Coal seam gas is shaping as a hotly fought state election issue in rural and regional NSW, amid public concern over the pollution of land, water and air.

Radio host Alan Jones, whose castigation of Queensland's LNP government over coal mining is likely to have contributed to the party's electoral walloping, is a vocal opponent of coal seam gas mining near homes. Asked on ABC's Q&A program on Monday if he would take up the coal seam gas issue during the NSW election campaign, Mr Jones said the Baird government would have to "face the consequences" unless public concerns were addressed.

On August 31 last year, coal seam gas was released from a well about 200 metres from homes at Camden after a pressure valve was activated. Alarmed residents reportedly heard a loud hissing noise and smelt gas.

Emails show that on September 5, AGL told government officials that up to 100,000 standard cubic feet of gas were emitted over about two hours. This figure was not made public.

On September 30, AGL publicly released a report into the incident. It said about 10,000 standard cubic feet of gas was released – 10 per cent of its original estimate.

AGL supplied that figure to the Environment Protection Authority in mid-September, but took two weeks to release it publicly.

A spokesman for Energy Minister Anthony Roberts said AGL's initial estimate assumed gas flowed continuously. He said the lower figure, based on data from the well, more accurately assumed that the gas flowed intermittently.

However this is at odds with AGL's email to departmental officials, which said its initial estimate was based on the valve operating "not continuously".

An AGL spokesman said the initial figure provided to officials was a "conservative upper estimate" and the figure was revised down after further analysis.

He said natural gas was not toxic, and fire crews did not detect harmful levels of methane. The EPA is investigating the incident.

The gas was 96 per cent methane, with smaller amounts of carbon dioxide, nitrogen and ethane.

Lock the Gate Alliance western Sydney co-ordinator Dan Robins, whose organisation obtained the documents, said the public should have been told immediately that a large amount of gas was potentially released, adding AGL was "not transparent, they are not upfront with the community".

He said coal seam gas was flammable and posed a significant risk to human health and the environment.

Camden Liberal MP Chris Patterson said only accurate data should be released to the community, however "the minute AGL have accurate information, it needs to be in the public domain".

The criticism follows the suspension of an AGL coal seam gas project near Gloucester last month after toxic chemicals were detected in water from two wells. The EPA criticised AGL for taking 12 days to alert the public. AGL said the chemicals were likely to be naturally occurring.

The documents also revealed a series of safety incidents at the Camden site between 2010 and 2014.

They include a sudden release of gas that caused skin damage to the chest, neck and face of a worker, and the leak of up to 1000 litres of produced water, which is salty and sometimes contains traces of drilling chemicals.

In 2013, a contract rig manager was found to have worked 21 days straight, plus two days travelling to and from the site. Other issues included duct tape used to secure a hand rail and objects lodged in wells.

Last October, Fairfax Media reported leaks had been found at almost one in 10 gas wells at Camden.

An AGL spokesman said the company was committed to safety and most issues related to "normal inspection, maintenance and servicing". He said the water leak was contained and corrective action was taken on several occasions.

A spokesman for Mr Roberts said the accidents were investigated and AGL was directed to act "to ensure the safety of its workers".