Italy’s far-right Northern League has promised to introduce mass deportations of asylum seekers to Africa as part of a radical reshaping of migration policies if it wins next month’s elections.

The party, led by Matteo Salvini, would also seek to force asylum courts to disregard the circumstances of a migrant’s journey in any deliberation about whether they should be granted asylum.

With Italians going to the polls on 4 March, and in the aftermath of an attack on six African immigrants, rhetoric on the right has increasingly focused on migration and Italy’s role as the point of arrival for hundreds of thousands of migrants crossing the Mediterranean from Africa.

The government, currently led by the centre-left Democratic party, has recently taken controversial steps to sharply reduce the number of migrant arrivals, including allegedly making secret agreements with militias and tribes in Libya that have been condemned by human rights groups.

But the Northern League, or Lega, has promised to go further, saying that, if elected, it would begin a programme to force an estimated 400,000 migrants back to their countries of origin, including Nigeria, Tunisia and Morocco.

Analysts have said they doubt the plan is realistic, and that the prospect of mass deportations in Europe would cause an uproar in Brussels. The current government has already sought to speed up the expulsion of migrants, but the process is expensive, mired in bureaucracy and complicated by the unwillingness of other countries to take back those who have left.

Marco Minniti, the interior minister, has said he wants to increase expulsions, but Italy only deported about 6,500 people last year, up from 5,200 a year earlier.

Lega’s campaign promises could shape domestic and foreign policy in the event of a victory by its centre-right coalition with Forza Italia and the far-right Brothers of Italy.