India has toughened its stand over Italy's refusal to send back its two marines to face trial in the killing of Kerala fishermen.

Highly placed government sources said that senior diplomat Basant Gupta who has been named ambassador to Italy, has been asked to stay put in India. Mr. Gupta was held back just a day ahead of his taking charge in Rome in what is effectively a retaliatory move by India.

The move is seen as part of a review of bilateral ties in the wake of Prime Minister Manmohan Singh telling Parliament on Wednesday that Italy's decision to go back on its commitment to the Supreme Court, will have its consequences.

Mr. Gupta had earlier been asked to expedite his departure to Rome because the government felt his presence there would help in coordinating with Italy in the AgustaWestland chopper kickback investigations.