Bharatiya Janata Party (BJP), which opinion polls show is on course to win the most seats in an election starting April 7

(Reuters) - India's main opposition party would welcome more foreign direct investment in defense, if elected, but would delay opening up big-box retail to global players now barred from the country's market of more than 1.2 billion people.

The nationalist Bharatiya Janata Party (BJP), which opinion polls show is on course to win the most seats in an election starting April 7, would also introduce a general sales tax and overhaul the financial sector, its manifesto is likely to say.

The BJP's candidate for prime minister, Narendra Modi, is campaigning on his economic record in running his home state, Gujarat, where the party trumpets an unemployment rate of less than a third of the national average.