Modi on Wednesday said the former prime minister used INS Viraat as a private taxi and his in-laws were onboard the aircraft carrier.
"The claim was totally wrong," said Vice Admiral (retd) Pasricha.
Former Navy Chief Ramdas, who was the Southern Navy Commander, in a statement, said no foreigners visited INS Viraat and that Rajiv Gandhi and his wife were onboard the aircraft carrier following all official protocol.
"Prime Minister and Mrs Gandhi were embarked on board INS Viraat off Trivandrum enroute Lakshwadeep. The Prime Minister was at Trivandrum as chief guest for the National Games prize distribution," the former Navy Chief said.
"He was going to Lakshadweep on official duty, to chair a meeting of IDA (Islands Development Authority). This meeting is held alternately in Lakshadweep and in Andamans," he said.
Admiral Ramdas, added, "There were no foreigners with them. I, as Flag officer Commanding in Chief, Southern Naval Command, based in Cochin, also boarded INS Viraat."
There were no parties held on INS Viraat or any of the other four warships accompanying the erstwhile aircraft carrier of the Indian Navy and no foreigners accompanied Rajiv Gandhi nor was current Congress President Rahul Gandhi present then, Admiral Ramdas said.
The former Navy chief stated, "During his visit to Bangaram on the last day, a few naval divers had been sent ashore for the PM’s safety. No ships were specially diverted for the personal use of the Gandhi family. Only one small helicopter was left at Kavaratti to meet any emergency medical requirements of the PM and his wife."
Aircraft carrier INS Viraat was commissioned into the Indian Navy in 1987. After nearly 30 years of service, it was decommissioned in 2016.
Another former senior Navy officer termed as 'untrue' Modi's claim that the Gandhi family used Navy's aircraft carrier INS Viraat as its "personal taxi".
"Due to such claims, even the truth coming from such people (Modi) would be seen as fake information," Vice Admiral (Retd) I C Rao.
Rao, who was the admiral superintendent of the Naval Dockyard in Mumbai in 1987, said, "It is very bad for politicians to make such allegations. I feel that with such continued series of claims, even the true information would be seen as fake."
"Such statements are aimed at swaying the voters. I feel the voters should ignore such claims and exercise their right," Rao said.
"Rajiv Gandhi along with his family boarded the ship from Thiruvananthapuram to stay aboard for three days.
Lakshadweep island is almost 220 nautical miles from land and helicopter was the only means of transportation then available, so he used the air service from Viraat, he said.
"He organised a dinner on board the ship for the ship's crew. It is very bad to spread fake information for some political gain," he said.
"I am not a fan of Rajiv Gandhi or his policies, I do not want Navy or any other establishment to be used for political gains," Rao said
You have made IAF jets your 'own taxi': Congress to Modi
The Congress accused Modi of making Indian Air Force jets his "own taxi" and paying "as low as" Rs 744 for using IAF aircraft for election trips.
Congress' chief spokesperson Randeep Surjewala cited a media report to attack the prime minister. "Distraction and fakery is your last resort. You have made Indian Air Force jets your own Taxi! You have paid as low as Rs 744 for using IAF jets for election trips!" Surjewala said.
"Scared of your own sins haunting you, you are shamelessly pointing fingers on others!" he said, in an apparent reference to Modi's allegation that the late Rajiv Gandhi used INS Viraat as a "personal taxi" on a family vacation.
The media report, based on an RTI, said the Bharatiya Janata Party (BJP) paid a total of Rs 1.4 crore to the IAF for 240 "non-official domestic trips" made by Modi since the start of his tenure as prime minister till January 2019.
"In some cases, the amount paid seemed to be quite low. For example, the BJP paid Rs 744 for a 'H/P Balangir-H/P Patharchera' trip by Modi on January 15, 2019," the report said.
What PM Modi said
Addressing his first poll rally in Delhi ahead of the May 12 elections, Modi on Wednesday accused then Prime Minster late Rajiv Gandhi of using aircraft carrier INS Viraat and its personnel for vacations with his foreigner in-laws.
Modi said, "Who has been treating the forces as personal property? ...have you ever heard that a family goes for holiday on a warship? This has happened in our country. The 'naamdar' family used INS Viraat as its personal property. They insulted it."
INS Viraat was withdrawn from its place of deployment and sent to fetch the in-laws of Rajiv Gandhi before it was taken to an island where nobody was there to welcome them and all arrangements for them were made by the personnel of the aircraft carrier, Modi alleged.
The holiday continued not for one day, but for 10 days during which the warship remained stationed there, Modi added.
The Prime Minister then asked whether the presence of "foreigners on the warship did not amount to playing with the security of the country. Or was it allowed just because he was Rajiv Gandhi?"
(With inputs from PTI)