A handful of top mining executives have warned they will have to lay off scores of workers and prematurely close some mines unless the WA Labor Government's gold royalty increase is voted down.

In an escalation of the industry's campaign against the royalty hike, nearly a dozen executives from mining firms and other employers in the sector joined forces to warn of severe consequences if the policy was not blocked.

It was a rare show of unity from some of the state's biggest gold producers as they upped the pressure on the Liberals to block the royalty increase when it comes to a vote in Parliament.

Newcrest Mining's Sandeep Biswas says the increase will have a major effect on earnings. ( ABC News: Jacob Kagi )

The proposed increase announced in last month's budget would lift the royalty rate by 50 per cent.

Newcrest Mining managing director Sandeep Biswas warned the company's Telfer mine in the East Pilbara — one of the state's largest gold operations — was under "serious risk" from the royalty increase.

"Telfer is a marginal mine and if this increase proceeds, it will wipe out Telfer's earnings," Mr Biswas said.

"Telfer cannot sustainably absorb the royalty increase."

Miners criticise 'farcical' Labor job claims

Gold Fields chief executive Nick Holland said his company — the state's second largest gold producer — was one of many which could be forced to trim its workforce.

The mining executives banded together in Perth in a rare public show of unity. ( ABC News: Jacob Kagi )

"We employ about 1,600 people directly and the same amount of contractors. We are going to have to look at those numbers carefully to neutralise the impact," Mr Holland said.

"There is going to be an impact on jobs in the future … it is not going to be a small amount."

Northern Star Resources managing director Bill Beament said his firm could not absorb substantially higher royalty payments, given one of its mines lost $45 per ounce last year.

"To say there is not going to be a hit to jobs ... is very farcical," he said.

Both Treasurer Ben Wyatt and Premier Mark McGowan insisted yesterday that no jobs would be lost as a result of the royalty increase.

Campaign a waste of time: Wyatt

The unified showing from the industry was seen as an effort to escalate pressure on Parliament's Upper House to vote down the royalty hike.

With the Nationals and crossbenchers opposed to the policy, the Labor Government needs Liberal support to ensure the royalty increase survives.

The Liberals are yet to decide how they will vote, with a decision not expected until after a partyroom meeting on Tuesday.

Leader Mike Nahan said the Liberals were listening to the gold industry and related businesses to ascertain what impact a royalty increase would have.

"Tell us what the impact will be … it is an important issue," he said.

"The Liberal Party does not take lightly its role of passing money type bills in the Upper House, it takes it very seriously.

"And the request to block one, we take seriously."

Mr Wyatt said the miners were wasting their time with their campaign and insisted it would not change anything.

"I say to the mining industry, stop wasting millions of dollars on lobbyists and help Western Australia get back into a more sustainable fiscal position," he said.

"I will not be swayed."

The gold sector has ramped up its campaign against the royalty hike in recent days, running prominent advertisements warning of thousands of job losses if the policy is not blocked.