Italy on Saturday warned its nationals in India to be \"vigilant and cautious\" as a diplomatic row over two Italian marines who skipped bail while facing trial for murder deepens.The advice came a day after India\'s airports were put on alert to prevent Italy\'s ambassador Daniele Mancini from leaving the country, according to Indian home ministry sources.\"In connection with any protests, especially in Kerala state, related to the two sailors, citizens are urged to always maintain a vigilant and cautious attitude and stay away from any crowds,\" the Italian embassy said in an advisory notice on its a website.The warning reflected apparent Italian concern about a possible backlash after Rome refused to return the two marines charged with murdering two Indian fishermen in waters off the coast of the southern state of Kerala last year.Local Indian media reported that fishermen\'s groups in Kerala have staged protests against the decision not to return the sailors while state lawmakers have expressed outrage.India\'s Supreme Court on Thursday directed that the Italian ambassador, who struck a deal for the marines to go back home to vote in last month\'s Italian election, should stay in India until the next hearing about the dispute on Monday.Rome announced earlier in the week it was reneging on commitments to send back the two sailors, Massimiliano Latorre and Salvatore Girone, to face trial.Mancini had signed an affidavit giving his personal assurance that the two marines would return.The dispute has been a major embarrassment for the Indian government and Prime Minister Manmohan Singh, who has warned of \"consequences\" for bilateral ties if the pair do not return to stand trial in New Delhi.Singh\'s rivals have accused the government of incompetence for allowing the marines to go home while facing such serious charges, and the main opposition Bharatiya Janata Party has said Italy is treating India \"like a banana republic.\"The marines shot dead the fishermen off India\'s southwestern coast 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.Italy insists the marines should be prosecuted in their home country because the shootings involved an Italian-flagged vessel in international waters, but India says the killings took place in waters under its jurisdiction.Ties between the two countries have also been soured by corruption allegations surrounding a $748 million deal for the purchase of 12 Italian helicopters which the Indian government is now threatening to scrap.India\'s foreign ministry said on Friday the \"entire expanse of our interaction\" with Italy is being reviewed while stressing that Italy has to \"respect and abide\" by the agreements between it and the Supreme Court.