India is downgrading its diplomatic ties with Italy and has asked its Ambassador- designate to that country Basant Kumar Gupta, who was scheduled to leave for Rome today, not to proceed to take up his posting.

The government which is reviewing the entire gamut of bilateral ties has decided to with-hold posting of Gupta, who was expected to take charge by end of next week, after Italian government reneged on its promise to send back two marines, facing trial for allegedly killing two Indian fishermen.

Accusing Italy of violating diplomatic norms and breaching assurance given to the Supreme Court, the highest court of the land, the sources said it was totally "unacceptable" and India was looking at downgrading its ties with that country to express its unhappiness.

"The decision of not sending Mr Gupta to assume his position is tantamount to the fact that India wants to keep diplomatic ties with Italy at a level lesser than the Ambassador," the sources said.

Gupta was named successor to Debabrata Saha, who retired in December last.

Meanwhile, all the exit points, including airports across the country have been alerted to prevent Italian Ambassador Daniele Mancini from leaving the country. The decision was taken by the Union Home Ministry a day after the Supreme Court restrained the Italian Ambassador from leaving India without its permission, official sources said.

Yesterday, the government had also announced decision to initiate review of entire gamut of relations with Italy which includes diplomatic, trade and defence ties apart from reaching out to European Union, which was briefed on India's views and position in the matter.

Official spokesman in the Ministry of External Affairs said the "entire expanse of our interaction" with Italy was being reviewed while stressing that Italy has to "respect and abide" by the agreements between it and the Supreme Court.

The apex court also issued notices to Mancini and the two marines --Massimiliano Lattore and Salvatore Girone-- and asked them to file their response by March 18 and posted the matter for further hearing next Monday.