According to a Facebook posting by Catholic priest Father Gregory Chan, the incident happened before the 6.30am mass.
It is learnt that one of the nuns, identified as Sister Juliana Lim, is warded at the Seremban Hospital and is in critical condition.
The other nun who was attacked was Sister Mary-Rose and she is said to be receiving treatment for various injuries.
Both nuns from the Infant Jesus Convent, were left bruised, bleeding and in shock following the attack, said Fr Chan in his Facebook posting.
The priests had also posted this message on his Facebook page four hours ago:
"My dear friends, please pray for two of our IJ sisters - Srs. Julianna & Mary-Rose - who were viciously attacked & seriously injured in our Church grounds early this morning before Lauds & Mass had begun.
"The ambulance came for them. After masses at Visitation & Mt Carmel, I rushed to the Emergency Ward, & saw them bruised, bleeding & in shock.
"One is critical & on a respirator. As I anointed them, tears streamed down my face. I couldn't help it. How wicked it is to do this to our nuns, who have given their whole life to God. Nevertheless, let us pray for God's forgiveness upon them, & for their eventual conversion."
Fr Chan could not be reached for further comment.
Meanwhile, a news portal reported Seremban police chief Assistant Commissioner Zainal Abu as saying that the attack on the nuns was being investigated.
The Council of Churches of Malaysia (CCM) today expressed shock over the attack on the nuns.
"The voices of antagonism and hatred have been on the increase in the country and it would be no surprise if the attack on the nuns were not conspired by those out to cause inter-religious conflict in the country.
"The police must investigate this case of outright religious intimidation and fear creation and bring those responsible to justice," said CCM general-secretary Reverend Hermen Shastri in a statement.
He said Christians throughout the country will pray for the two sisters, “that God will grant them peace in their hearts and a speedy recovery from their physical trauma”.
"May the Lord look down in mercy on those who have caused hurt to the two innocent sisters," Shastri added. – May 14, 2014.