The Congress on Sunday demanded an apology from Prime Minister Narendra Modi and BJP chief J P Nadda over BJP spokesperson Prem Shukla's usage of "indecent language" for Sonia Gandhi, and warned of filing a defamation suit in case this is repeated.

In a letter to BJP chief Nadda, Congress general secretary Jairam Ramesh said the Congress registers its strong objection to the "abusive and indecent" language used for Gandhi by Shukla during a discussion on a national news channel on July 23.

Top leaders and spokespersons of BJP, who talk about culture, have repeatedly used objectionable language against respected women of the country, especially the 75-year-old president of a national party, Ramesh said.

"Using abusive words for the leaders of the opposition shows the anti-women thinking of the BJP. Due to such objectionable remarks, the level of politics of the country is going down," he said.

Respect for women has been a great tradition of India since Vedic times and therefore decency in politics and respectful behaviour towards women is naturally expected from the ruling BJP, but the party has repeatedly disappointed us with its language and behaviour, Ramesh said in his letter to Nadda.

"Our appeal to Prime Minister Modi ji and you is to apologise to the women of the country for the shameful and indecent rhetoric of your party leaders, as well as ask your spokespersons and leaders not to hurt the dignity of politics and refrain from abusive language," he said.

"The repetition of inappropriate language for our President or any other leader will force us to take legal steps such as a defamation suit," Ramesh warned.

Earlier, in a statement, Ramesh said the remarks by Shukla had exposed the BJP's 'anti-women' face.

The objectionable language of the BJP's national spokesperson shows that the BJP neither has respect for women, nor does the party believe in decency in politics, Ramesh said.

This is not the first time a BJP leader has used abusive language against women, he said.

The country knows that many BJP leaders, including Prime Minister Modi, have made "objectionable" comments against the respected women of the country and especially opposition leaders, he alleged.

"When a person holding a high office like that of the prime minister lowers the dignity of that office, the spokesperson of his party will naturally use abusive words for opposition leaders," Ramesh said.

"Till date Prime Minister Shri Narendra Modi has not apologised for his inappropriate words. The level of politics of the country is continuously deteriorating due to this type of disrespect and shameful rhetoric," he said.