President Donald Trump is ratcheting up the pressure on India, calling into question the prospects of a deal with a key US trading partner just days before his tariff deadline.

The president said Wednesday morning that imports from India would be subject to a 25 percent tariff as of Friday, as trade talks between the countries hit a stumbling block.

He said India, which has the world's fifth largest economy, will also face an unspecified penalty but did not elaborate on the amount or what it was for.