Sonia Gandhi, the Italian-born head of India's ruling party, accused Rome of an unacceptable "betrayal" Tuesday as she waded into a bitter dispute over two marines who have skipped bail.
Gandhi told a Congress party meeting that she supported any move to ensure the two marines return to India to face murder charges after Rome reneged on an earlier undertaking to India's Supreme Court from the Italian ambassador.
"The defiance of the Italian government on the question of the two marines issue and its betrayal of a commitment given to our Supreme Court is outright unacceptable," Gandhi said in New Delhi.
"No country can, should, or will be allowed to take India for granted," said Gandhi, the widow of slain former prime minister Rajiv Gandhi.
Italy has accused India of violating laws on diplomatic immunity by preventing the ambassador, Daniele Mancini, from leaving the country.
But Gandhi, India's most powerful politician, who took Indian citizenship in 1983, said action had to be taken to ensure the pledge to return the marines is fulfilled.
"All means must be pursued to ensure that the commitment made by the Italian government before the Supreme Court is honoured," said Gandhi in her speech, a copy of which was obtained by AFP.
The marines, Massimiliano Latorre and Salvatore Girone, are accused of shooting dead two fishermen off the southwestern state of Kerala in February last year, when a fishing boat sailed close to an Italian oil tanker they were guarding.
They say they mistook the fishermen for pirates.
Gandhi's comments on Tuesday were her first on the affair and came after opposition accused her of conspiring to help the marines evade justice.
A local leader of the main opposition Bharatiya Janata Party was quoted last week as saying Gandhi "plotted" to help the marines, while a communist lawmaker in Kerala said that "secret hands of Italy' had been working on their behalf.
The pair had been given permission to fly home to vote in last month's Italian general election on the condition that they would return and present themselves before a judge in New Delhi where their case is being heard.
But the Italian foreign ministry announced last week that the men would not return in view of what it described as a "formal international controversy" between the two countries.
New Delhi has warned of "consequences" and is reviewing its ties with Italy, while the case is being watched carefully internationally because it could set precedents over the treatment of foreign diplomats.
India has put its airports on alert to prevent Mancini from leaving the country and the Supreme Court issued instructions that "appropriate steps" should be taken to restrain him.
Without diplomatic immunity, he could be prosecuted for contempt of court.