Indian Prime Minister Manmohan Singh Wednesday demanded that Italy return two marines charged with murdering two fishermen to face trial in the country.

In a strongly worded message, Singh warned "there will be consequences," if Italy fails to adhere to its commitment given to the Indian supreme court.

The diplomatic tussle between India and Italy erupted Monday after the latter said a pair of Italian marines, who were allowed to travel home for casting votes in the national elections will not return to Delhi to face trial. 

Italy’s decision on the issue has outraged India, which said it takes the “breach of trust” seriously.  In a statement made in the Indian parliament Wednesday, Singh observed that Italy's conduct on the issue was unacceptable and would affect the bilateral relations.

“They have to return the two accused as directed by the Supreme Court. We will treat this matter with seriousness and it will affect relations in between the two countries," Singh told parliament.

"They violated every rule of diplomatic discourse and call into question solemn commitments given by accredited representative of a government," the prime minister added.

The marines, Massimilian Latorre and Salvatore Girone were allowed to leave India based on a sovereign undertaking given to Indian supreme court on behalf of the country by the Italian envoy, Daniele Mancini, that the duo will be sent back to face trial within four weeks.

Indian government was left embarrassed after Italy said the marines won’t be sent back to India and the issue has caused uproar in the country with opposition blaming the government for letting the accused escape trial in the country. Opposition parties demanded appropriate retaliation measures against Italy, worsening the already strained bilateral ties between the nations.

According to the sources, India is mulling various measures including sending back the Italian envoy, closing down all diplomatic missions in Italy and penalizing the Italian companies.

Indian government had summoned Mancini, Italian envoy and expressed its disappointment over Italy’s decision to dishonor the commitment. Citing sources, the Press trust of India (PTI) reported he may be expelled from the country.

However, Mancini who had guaranteed the return of the marines to the supreme court, expressed confidence that the issues between the countries will be solved diplomatically.

"There are some difficulties between the two countries, we are working with the Indian institutions and the government on this in order to do whatever we can and overcome this. I am confident that like two mature democracies we will be able to overcome these difficulties," he said.

In another development, senior lawyer Harish Salve, who has been representing the Italian marines in the court, said he will not represent the marines anymore in the fishermen killings case, as Italy’s decision amounted to breach of faith.

 "I have informed the Italian ambassador that it will no longer be possible for me to appear or be associated with this case,” Salve said in a statement.

 "I consider this action of the Republic of Italy as a breach of faith. It is my perception that the Italian Government should have, in the least, forewarned its Indian lawyers of the change of its position before communicating it to the Government of India," he added according to a report in CNN-IBN, a leading Indian television channel.

The situation has emerged tricky for the Congress-led UPA government as Sonia Gandhi, the leader of the ruling party is of Italian origin, and the right-wing opposition parties in the country in the past have often referred to her Italian connection to accuse the government of colluding with Italy.    

Opposition party leader Sushma Swaraj, Wednesday tweeted: "It is not a case of diplomatic standoff. It is one of diplomatic send off."

Italian Media Attack Country’s Government

 In an interesting move, the Italian media attacked the Italian government Tuesday, blaming the government’s handling of the issue has tarnished country’s credibility overseas.

The Rome daily La Repubblica said the move by Premier Mario Monti's caretaker government "dealt a terrible blow to our credibility from the point of view of international image," the Associated Press reported.

The newspaper said the decision made the fishermen victims twice: "First by the tragic misunderstanding, then by a fraudulent behavior on the part of a country that should in any case take responsibility for what happened."

Italian government had justified their decision saying, “India had not responded to its written offer for diplomatic negotiations.”

The marines were guarding an Italian tanker off the Kerala state coast in February last year, and shot dead two fishermen, who they apparently mistook for pirates. Italy claims the shooting took place in international waters, while the Indian Supreme Court ruled that killings happened within India’s jurisdiction.