Indian Foreign Minister Sushma Swaraj on Tuesday assured lawmakers that New Delhi would go "out of its way" to save sentenced spy Kulbhushan Jadhav from death row in Pakistan, according to Indian media reports.

Calling Jadhav "a son of India", Swaraj issued a warning to Pakistan saying, "I would caution the Pakistani government to consider the consequences for our bilateral relationship if they proceed on this matter."

"Our position is very clear, there is no evidence of wrongdoing by Kulbhushan Jadhav," Swaraj told the Rajya Sabha, the upper house of the Indian parliament.

"This is an act of premeditated murder," she said, referring to the death sentence handed to the Indian spy by a Field General Court Martial (FGCM) on Monday.

Swaraj assured parliamentarians that the government would not stop at just ensuring Jadhav has the best of lawyers to fight his case in the Supreme Court, but would "go out of the way to save him".

When asked by a lawmaker if the government would fight Jadhav's case in the Pakistani apex court, Swaraj said: "We will do more. We will take it up with the president [Mamnoon Hussain]," The Hindu reported.

The Indian minister of external affairs, Swaraj, alleged that Jadhav was awarded the death sentence on "concocted charges".

"Jadhav was doing a business in Iran and he was abducted and taken to Pakistan. We sought consular access, but were denied," she claimed. "He is innocent. They [Pakistan] seek through him to cast aspersions in India to hide their own role in terror."

Explore: Who is Kulbhushan Jadhav?

The lower house of the Indian parliament, the Lok Sabha, was united in condemning Jadhav's sentence.

Indian Home Minister Rajnath Singh, addressing the Lok Sabha, said: "I condemn it [Jadhav's death sentence] as an illegal act against the norms of the rule of law and international convention."

"Whatever has to be done to do justice with Kulbhushan will be done by the government," he added.

Jadhav's arrest and trial

Indian spy Kulbhushan Jadhav was arrested on March 3, 2016, through a counter-intelligence operation in Balochistan's Mashkel area for his involvement in espionage and sabotage activities against Pakistan, the Inter-Services Public Relations (ISPR) said in a statement on Monday.

Although the accused had been provided with a defending officer as per legal provisions, according to ISPR, Pakistan had turned down India's request seeking consular access to Jadhav last year due to his involvement in "subversive activities" in the country.

Jadhav was tried by the FGCM under Section 59 of the PAA and Section 3 of the official Secret Act of 1923, the statement said.

Jadhav confessed before a magistrate and court that he was tasked by Indian spy agency Research and Analysis wing to plan, coordinate and organise espionage and sabotage activities seeking to destabilise and wage war against Pakistan through impeding the efforts of law enforcement agencies for the restoration of peace in Balochistan and Karachi, the ISPR said.

Following the announcement, India summoned Pakistan's High Commissioner to New Delhi Abdul Basit on Monday and handed over a demarche saying, "If this sentence against an Indian citizen, awarded without observing basic norms of law and justice, is carried out, the government and people of India will regard it as a case of premeditated murder."

Dawn reported that Jadhav now has 40 days to file an appeal against the FGCM in the army’s court of appeal, according to retired Col Inamur Rahim, a military law expert.

In case the appeal court upholds the FGCM verdict, Jadhav would have the opportunity to seek mercy from the army chief and the president of Pakistan.

Simultaneously, Col Inam said, the convict could approach a high court if he felt that due process was not observed during his trial and his fundamental rights as an accused were not fulfilled.

Experts view the military's announcement about Jadhav's trial and prosecution as an unprecedented move, viewing it as a strong message to India as well as other foreign intelligence agencies.