Director-General Tim Davie of the BBC assured employees in India that the organization would continue to report impartially and without fear or favor.
It comes after searches conducted by tax authorities at BBC offices in Delhi and Mumbai.
The importance of reporting objectively was emphasized by Mr. Davie, who also thanked the staff for their bravery.
Recently, a documentary attacking Indian Prime Minister Narendra Modi was broadcast on the BBC, which is helping with the investigation.
The Indian government referred to it as "hostile propaganda" and made an effort to prevent it from airing domestically.
Mr. Davie claimed that the BBC would aid employees in performing their duties safely and effectively.
Nothing, he wrote in the email, is more crucial than our capacity to report without fear or favor.
"Our responsibility to our global audiences is to produce and share the best original content while pursuing the facts through independent, unbiased journalism. We won't put off completing that task.
"Let me be clear: the BBC is purpose-driven; we don't have an agenda. And our primary objective is to serve the general public by disseminating unbiased news and information that will enable them to comprehend and participate in the world. " .
Tax officials conducted what they called a "survey" at the BBC offices for three days.
The Central Board of Direct Taxes in India reported that it had discovered "discrepancies and inconsistencies" in addition to proof "that tax has not been paid on certain remittances which have not been disclosed as income in India by the foreign entities of the group.".
Opposition MPs in the UK called the raids intimidating and deeply concerning earlier this week.
Despite stating that "we continue to follow the matter closely," a Foreign Office minister declined to comment on the claims made by India's income tax department.
