Hajia Fati created a scene at the party's headquarters after slapping a journalist with Accra-based radio station Adom FM.
The NDC in a statement issued by the National Communications Director, Solomon Yaw Nkansah said it is equally enraged by Hajia Fati's subsequent explanation that she thought the female journalist was an onion seller rather than a reporter.
He said the party "is appalled and outraged at the shameful and brutal assault" on the journalist.
Hajia Fati created a scene at the party's headquarters after slapping a journalist with Accra-based radio station Adom FM, when Sammy Crabbe went to pick his nomination forms last Friday.
She said, she slapped Ama Sekyiwaa because the reporter did not introduce herself adding that she had not sought her permission before taking pictures.
She said "She was snapping [taking pictures of] me, I don’t know her, she didn’t approach me, she didn’t tell me anything. I only saw a flash on my face twice, the third time, I slapped her because I didn't know who she was."
But the NDC condemned the act and said Hajia Fati has become infamously notorious for unleashing violence at the NPP headquarters.
The party stated that "The NDC condemns the assault on Miss Sakyiwaa in the strongest possible terms. Democratic Ghana, which currently occupies the top spot in Africa on the Freedom of the Press index, cannot continue to record such dents especially at the headquarters of the ruling party."
The NDC also deplored "the lack of courage and decisiveness by the NPP in condemning and reprimanding Hajia Fati in a timely and sincere manner considering that the unwarranted violent conduct of their leading member took place in the open right in front of some top executives of the NPP."
"This is the reason we find the use of the term 'alleged' in the NPP's under-pressure, belated and weak statement as most offensive and insensitive to Miss Sakyiwaa," the statement added.
The party has called on the Police to, as a matter of urgency, investigate and take immediate action and also apprise the nation on the outcome of investigations of other recent attacks on journalists at the party's head office.
"We wish to afford this opportunity to remind the police that the NDC and the general public, particularly the Ghanaian media fraternity, [are] running out of patience as we await their report on Latif Iddrisu who sustained injuries at their hands when our Deputy General Secretary Koku Anyidoho was arrested.
"The NDC demands that President Akufo-Addo takes steps to stem the lawlessness, violence, bloodletting and assault on press freedom that have become synonymous to his party's headquarters.
"We also condemn the attempt by Hajia Fati to create the impression that our nation's hardworking onion sellers can be justifiably attacked just because they sell onions. It is shocking that any leading member of the ruling party will have such a criminal mindset towards our dynamic market women whose taxes are used to fund the creature comforts of these NPP elites.
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"The NDC is equally outraged that the NPP has not as yet retracted and apologised to onion sellers and market women across the country. This is most reprehensible.
"Our thoughts and prayers are with Miss Sakyiwaa and all victims of violent attacks against the media. We also renew our solidarity with all onion sellers, market women and indeed the workers of our dear country. May justice be done in this matter," the party noted.