"I always thought Jaitley was a gentleman, but I am sorry to read about his shameless attempts to question the statehood of Gandhi when she had nothing to do about what I had said yesterday in a newspaper interview about Mr Jaitley," the former Chief Minister said in a statement.
"But let me remind Jaitley of our great Indian culture and tradition which accepts the daughters-in-law as the real inheritors of the house and not the daughters irrespective of which place they come from," the Congress candidate from Amritsar said while hitting back at Jaitley.
"Sonia Gandhi was married to late Shri Rajiv Gandhi 45 years ago and she obviously belongs to UP and India," Singh said.
"Every time you (BJP) have tried to rake up this issue (Sonia's origin issue) you have badly lost as people of the country have repeatedly rejected your chauvinistic and xenophobic rabble rousing," he said.
Arun Jaitley understands well he is badly losing: Amarinder Singh
Hitting out at Singh for calling him an "outsider" in Amritsar, Jaitley said, "Despite my ancestral roots in Punjab, Captain Sahib (Amarider) called me an ‘outsider' and a ‘pseudo' Punjabi. Will he be kind enough to tell me which state in India does (Congress President) Mrs Sonia Gandhi belong to?
"Regrettably, he is resorting to his old USP - lower the level of debate through personalised and discourteous language.... I have to resist the temptation of reciprocating in the same manner. However, a polite response is necessary," Jaitley wrote on his website.
Reacting to the remarks, Singh said it is too obvious as to who is lowering the level of debate by desperately trying to drag someone who has nothing to do in an argument.
"Jaitley understands well he is badly losing," he said.
Alleging that Jaitley's "newfound love" for his Punjabi roots was sheer opportunism, Amarinder asked if he had so much attachment with his "Punjabi roots", why did he need to go to MP to contest an election and why not Punjab.
"And let Mr Jaitely tell me when did he last visit Punjab, leave aside contesting an election from here," he asked.
Replying to Jaitley's charges on his accessibility, Singh said, "My accessibility and affection of people must be already known to you by now after the announcement of my candidature from here (Amritsar)."
"I don't want to say as to whose accessibility should be questioned; the one who has been in electoral politics for last four and a half decades or the one who has always chosen backdoor entry to the legislature," he added.
Jaitley, a Rajya Sabha MP, is contesting his first-ever parliamentary polls.
"My political office in New Moti Bagh Palace (Patiala) remains open seven days a week from 8 in the morning till 8 in the evening and Jaitely is welcome to visit anytime that suits his convenience and have a coffee with me," he said.
Taking a dig at Singh, Jaitley had said that the Congress leader had still not come to the constituency.
Jaitley had also said that after winning the polls, he will have both office and residential base in Amritsar.
Meanwhile, Jaitley, addressing a gathering on the occasion of martyrdom day of freedom fighter Bhagat Singh in Amritsar, said there was dire need to bring change in power corridor at the Centre.
"The need of the hour is to bring change at the Centre," he said while canvassing in the holy city. He also held series of meeting with the party workers to boost his election campaign, party sources said.
The BJP leader said it was right time to take the incomplete dream of Bhagat Singh to a logical conclusion by bringing change in the Central government as UPA has allegedly plundered the national exchequer.
Urging youth voters to exercise their franchise, he said that "youth of today's need to bring change with ballot, but not with bullet".
Each youth should come out to cast their votes as only voting exercise could replace UPA, he added.