Foreign Minister Sergei Lavrov said the New Start treaty "cannot be reopened, becoming the subject of new negotiations" according to remarks reported by Interfax news agency.

Republicans in the US Senate have recently pushed to change its wording. Two-thirds of the 100 US senators must back the treaty for it to be ratified.

"The Start agreement, which was drafted on the basis of strict parity, completely meets the national interests of both Russia and the United States," Mr Lavrov told Interfax.

In Washington DC, top Republican senators have pledged to oppose the treaty, with some objecting to the tight time frame before the new Congress begins in January and others saying they fear it will prevent the US from developing a missile defence system.

BBC