The NSW government has set up up an expert panel to build a case for lower immigration amid frustration the state is under population pressure.

Premier Gladys Berejiklian on Wednesday appointed the three-member panel to develop an NSW population policy to take to the federal government next year.

The group - made up of University of Western Sydney chancellor Peter Shergold, Infrastructure NSW CEO Jim Betts and NSW Department of Planning secretary Carolyn McNally - will be given two months to advise the premier on matters such as how long is needed for infrastructure to catch up with population growth rates.

Ms Berejiklian said NSW's economic success was attracting a "far greater" share of immigrants than it had in the past.

"It is becoming increasingly clear that the current high rates of population growth are putting even more pressure on our infrastructure," she said in a statement.

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"It is now time for us to take stock and get ahead."

She renewed her call to halve the overseas migrant intake to around 45,000 a year, as seen during the Howard-era, until a proper population policy is in place.

Ms Berejiklian has written to Prime Minister Scott Morrison requesting a special COAG meeting on population in 2019.