The Argentine government on Wednesday rejected demands that it change controversial agricultural export tariffs which have helped push up world soy prices 10 per cent and brought thousands of demonstrators on to the streets of Buenos Aires.

Noisy protests by farmers and their supporters on Tuesday night followed an uncompromising speech by President Cristina Fernández defending the new sliding scale of export tariffs on grains and cereals, which she called “profound measures to redistribute income”. Groups loyal to the government also took to the streets and there were isolated clashes.