Social media giant Facebook admitted Friday it has to do better to curb hate speech as it battled a storm over how it handled comments by a member of India's ruling party who called Muslims traitors.

"We've made progress on tackling hate speech on our platform, but we need to do more," Facebook India's managing director Ajit Mohan said in a statement that denied any bias.

Hindu nationalist lawmaker T. Raja Singh posted comments and made speeches saying that Rohingya Muslim refugees should be shot and Muslims were traitors.

Facebook has been caught in a growing controversy in its biggest market in terms of users since The Wall Street Journal reported that an executive refused to remove the comments because it would damage the company's business interests.

"Over the last few days, we have been accused of bias in the way we enforce our policies. We take allegations of bias incredibly seriously, and want to make it clear that we denounce hate and bigotry in any form," said Mohan.

The Facebook India chief defended his company's actions and said "we have removed and will continue to remove content posted by public figures in India when it violates our community standards."

"We will continue to invest in our efforts to combat hate speech on our services," he added.

Mohan did not give details however and his online post did not explain the case of Raja Singh, a member of Prime Minister Narendra Modi's Bharatiya Janata Party.

Facebook India's top public policy executive, Ankhi Das, told staff that hate speech rules should not be applied to BJP individuals and party allies even though the post had been flagged by staff, the Journal reported.

Mohan said that "decisions around content escalations are not made unilaterally by just one person". 

He insisted there were "robust checks and balances built in to ensure that the policies are implemented as they are intended to be and take into consideration applicable local laws."

"These policies are ever evolving to take into account the local sensitivities especially in a multicultural society such as India," Mohan said.

The BJP has not commented on the controversy though Raja Singh told one Indian newspaper his Facebook account had been hacked.

Opposition Congress party politicians have accused the company of favouring the BJP, and Facebook executives have been ordered to appear before an Indian parliamentary information technology committee on September 2.