The NSW government has announced up to $100 million in rebates to farmers purchasing the mouse control chemical zinc phosphide amid a plague of the rodent blighting rural and regional communities.

The move follows last month’s commitment of $50 million for the first support package.

NSW farmers will be offered a rebate of 50 per cent on their purchase of zinc phosphide – which is already tax deductible – up to $10,000.

Agriculture Minister Adam Marshall said in a statement the government was also chipping in $5 million to help transport zinc phosphide to Australia.

“The reason the government’s taking this action is based on new advice from the CSIRO indicating that this mouse plague could indeed be worse than anyone expected,” Mr Marshall said.

“Even the big cold snap happening across NSW may still not be enough to significantly dent mice numbers … before we get into the spring planting season.”

The NSW government last month secured 5000 litres of the anti-coagulant and super-strong mouse killer bromadiolone.

This was enough to treat about 95 tonnes of grain and would be provided to farmers for free once federal authorities approve its use.

The chemical is able to kill mice within 24 hours of consumption.

Another 6,000 litres are set to arrive from India within a fortnight.

Mr Marshall also announced that the government would put $5m aside to “shore up” the zinc phosphide supply chain and assist with international and domestic freight costs.

He said while there were no “major issues with availability”, supply was “patchy” in some parts of the state.

The rebates come in addition to household and small business rebates, which eligible residents and business owners can apply for through Service NSW.

-with AAP