Finance Minister Jaswant Singh said on Wednesday the value-added tax system cannot be implemented across the country until all preparations are completed.

"We cannot support the implementation of VAT until all preparations and groundwork are completed," Singh told Parliament.

He said the states should stick to the agreed principles and rates for the implementation of VAT across the country.

VAT is India's most ambitious tax reform in 50 years which aims to cut multiple layers of taxes. India has set June 1 for launch of VAT in many states.