New Delhi, June 11 -- In a double blow to India's trade diplomacy, the US has rejected New Delhi's second attempt within days to initiate consultations at the World Trade Organization-this time over steep tariffs on automobiles and auto parts.

Washington has turned down India's notice for WTO consultations on the US's 25% tariff on auto components, asserting that the auto duties were imposed on national security grounds and so are not subject to multilateral trade rules, as per a WTO paper.

This comes just days after the US brushed aside India's long-pending case on steel and aluminium duties. As with that dispute, New Delhi reserves its right to impose retaliatory duties on US automobile tariffs, an official with India's commerce minis...