India may test-fire a series of its most lethal surface-to-surface ballistic missile, Agni-III, this year, the country's top defence scientist, V K Atre, indicated on Tuesday.

"We have put in operation elaborate plans so that the test-firing is successful," Atre said in New Delhi.

Any failure in the launch of the missile, which has a range of 3,000 km, "would be a great setback to defence scientists", he added.

On the recent tests of the upgraded version of Prithvi-II, Atre said these missiles with an enhanced range of 250 km were test-fired successfully using indigenous global positioning system to give them greater accuracy.

He rejected that there was any move to change the propellant of the Prithvi missile from liquid to solid, saying such short-range missiles were more accurate with liquid fuel.

He also said that tests of the indigenous Light Combat Aircraft -- Tejas -- were on schedule.