Ashurst and Dickson Minto have advised on the share placing by FTSE 100 oil company Tullow Oil, which is expected to raise around £1bn.

The company will issue 80.4 million new shares, representing roughly 10% of the group's existing shares.

Ashurst advised the underwriting banks Merrill Lynch and RBS Hoare Govett as joint global co-ordinators and joint bookrunners, as well as BNP Paribas and Calyon as joint bookrunners.

The team at the City law firm was headed up by equity capital markets partner Steven Fox alongside corporate partner Daniel Bushner.

Dickson Minto was instructed by the company with corporate partner Colin MacNeil at the helm.

One partner that advised on the deal commented: "To have got this deal away is a sign of the strength and intent of the London market's appetite for oil and gas at the moment."

The money raised from the placing will go towards helping to fund the company's buy-out of Uganda's Heritage Oil and to provide development capital for Tullow's African projects. Tullow's market capitalisation on 28 January was £9.3bn.

Tullow has turned to a number of London law firms in the past, with Norton Rose being a major beneficiary. Last year the company set up a £2bn reserve-based lending facility and launched a £402m rights issue. Norton Rose advised the company, with Herbert Smith in for the lenders on the facility, while Linklaters advised the underwriters.

In 2005 Norton Rose also worked on Tullow's $850m (£523m) financing, on which partner Lucy Wolley Dodd led and Herbert Smith advised the lenders.