Almost 500 people from across New South Wales have rallied in the pouring rain outside Parliament House against proposed changes to legislation which would give police greater powers at coal seam gas protests.

The State Government wants to give police increased powers to search protesters for devices used to chain themselves to equipment, and then seize them to stop them from "locking on".

It also plans to increase the fine for aggravated unlawful entry on enclosed lands to $5,500 and protesters could face jail sentences of up to seven years.

Greens NSW mining spokesman Jeremy Buckingham welcomed the protesters, who labelled the changes "draconian".

"Thank you all for coming out in this wonderful rain to protest," he said.

"This is New South Wales, this is not Putin's Russia."

Farmer Don McKenzie travelled from Coonamble in the state's west and has participated in coal seam gas protests in the Pilliga previously.

"Mr Baird, we stand before you today because we have been betrayed by the political system," he said.

Protesters vow to continue if changes pass

Mr McKenzie, along with anti-coal seam gas groups, said they would not be deterred if the changes came into effect and vowed to continue to protest.

Protesters said they would not be deterred. ( Supplied: Facebook )

"Heaven knows how we are going to pay their fines," Anne Thompson from the group Knitting Nannas said.

"We can't afford $5,500 on our pensions.

"We're already making jailbird outfits."

The Government said it wanted to stamp out unsafe activity and stop extremist forms of protesting.

The NSW Minerals Council said the new measures were necessary because of concerns for the safety of workers and protesters.

Opposition says plan is 'disgraceful'

The bill was debated in the Lower House this afternoon and is expected to go to the Upper House tonight.

Labor MP Ryan Park said the bill would destroy the fundamental right to protest.

"This Government not only wants to ride roughshod over democracy, it wants to ride roughshod over men and women who have done nothing other than believe they are doing everything possible to protect the sensitive farming, agricultural and water that is so important to our state," Mr Park said.

But Nationals MP Kevin Andrews dismissed suggestions the bill curtailed a person's right to protest.

"We believe in the democratic right to protest but what we don't believe in is putting people's lives at risk.

"What we don't believe in is putting their lives at risk and the people around them at risk," he told Parliament.