In a statement from London, the company said the open offer price is fixed at Rs 600 apiece, but added that the company will offer a Rs 6 bonus per share.

Currently, Unilever holds 52.48 percent in HUL and post open offer it will go up to 75 percent.

It can be noted that on April 30, the Anglo-Dutch consumer goods giant had said it would pump in USD 5.4 billion or over Rs 29,380 crore in HUL to hike stake in its holding in the domestic arm to 75 percent through an open offer, and offered Rs 600 a share, which was 21 percent higher than HUL's closing price of Rs 497.35 the previous day, when it had announced the annual numbers.

The world's second-largest consumer goods company "is making a voluntary open offer to acquire 48,70,04,772 shares representing 22.52 percent of the total voting share capital from the public shareholders of Hindustan Unilever", Unilever said.

HSBC Securities & Capital Markets India is the manager to the offer.

In January this year, Unilever had decided to hike royalty fees from HUL. As per an agreement between HUL and Unilever for the provision of technology, trademark licences and other services, royalty payment by the Indian arm to its parent will increase to 3.15 percent of turnover by the financial year ending March 31 2018.

Earlier, HUL was paying a royalty of 1.4 percent of the turnover. The agreement became affective from February 1, 2013.

In the March quarter, HUL has reported a 15 percent spike in net profit at Rs 787 crore, while for the full year, its profit rose to Rs 3,829 crore, an increase of a whopping 37.20 percent as against Rs 2,790.66 crore in 2011-12, while net sales for 2012-13 rose to Rs 26,317.15 crore from Rs 22,987.73 crore in the previous fiscal.

Subject to approval of the final dividend of Rs 6 per share recommended by the HUL board for the FY13, and of the AGM slated for July 26, the shareholders who tender their shares in the open offer will be entitled to receive the final dividend in respect of the shares tendered by them, the statement said.

HUL shares closed flat but with a negative bias at Rs 593.15, a fall of 0.27 percent, on a day when the Sensex tanked 2.74 percent or 526.41 points to 18719.29.

PTI