Border guards in the area requested help from the army Super Puma for the night-time search by infrared, said local radio in a report that was subsequently confirmed by newspaper 20 Minuten.
As yet it is not known if anyone was caught in the search.
The cost of the helicopter – 10,900 francs an hour – was criticized by Green politician Balthasar Glättli.
“With that money we could have employed a border guard for half a year,” he told 20 Minuten.
He also accused the search of being something of a publicity stunt by the right-wing Swiss People’s Party (SVP).
“I suspect the SVP federal councillors are using such dramatic action to fan the flames of the asylum issue during the summer silly season,” he said.
SVP politician Thomas Hurter rejected the claims, saying “we owe it to the Swiss people” to control the borders.
Contacted by the paper, the Swiss border guards office confirmed the operation, saying it aimed to fight against illegal immigration.
However it said the army regularly helps them out and that a certain number of helicopter hours are allocated to it each year, paid for by the federal defence office, meaning this latest intervention would have simply been deducted from its quota.
The news comes a day after it was reported that a record number of illegal immigrants crossed into Switzerland from Italy during the first week of July.
And on Tuesday some 60 migrants, mostly Eritrean, were caught by border guards on a train in Bellinzona, after travelling from Milan, reported news agencies.
It’s the biggest number of illegal immigrants to be found on a single train, said border guards.
They were taken back to the Swiss border with Italy at Chiasso, where they can either claim asylum or will be deported back to Italy.
Asylum figures fall
Though illegal immigration remains a problem, the number of migrants requesting asylum in Switzerland – a legal process – has actually fallen for the second quarter in a row, said the Swiss migration office (SEM) on Tuesday.
According to figures released by the SEM, 5,962 asylum requests were lodged in the last quarter, a 20 percent drop on the same period last year.
The asylum seekers were mainly from Eritrea, Syria and Somalia, said the report.
The fall continues a trend, after the number of asylum seekers dropped by 45 percent in the first quarter of this year.
Nevertheless, the SEM said it could not make an accurate prediction for the total number expected to arrive this year, given the migrant situation is volatile and therefore “unpredictable”.
Consequently, the cantons should remain on alert, SEM chief Mario Gattiker said in an interview with the NZZ newspaper.
In April the Swiss federal government drew up plans detailing how the country would deal with three potential migrant scenarios ranging from 10,000 arrivals inside a month to a worst case of 30,000 over a few days.
The latter would require army intervention, the government said at the time.
Currently the country is “a long way” from this sort of emergency situation, Gattiker told NZZ.
But the country’s preparations for such a situation mean it is “better armed” to deal with a potential large influx of migrants than it was the previous year.