Capital MS&L has been called in to support what is likely to be the City's largest float for two years.
Indian conglomerate Essar Energy has handed the agency a brief to manage comms around a forthcoming $2.5bn (£1.6bn) IPO on the London Stock Exchange, which would catapult the firm into the FTSE 100.
The firm is owned by billionaire brothers Ravi and Shasho Ruia, who are looking to sell between 20 and 25 per cent of the business in the biggest overseas IPO by an Indian business.
Capital is understood to have won the brief without a competitive pitch, having built a relationship with the firm through previous project work since last year. Richard Campbell, co-MD of Capital MS&L, is leading the account.
City agencies have benefited from a number of significant IPO briefs in recent times, but many of the highest profile listings, such as Merlin Entertainment, New Look and Travelport, were pulled. However, Brunswick-advised New Look is said to be resurrecting its listing plans.
A key comms component of the Essar Energy listing will be to differentiate Essar from heavily indebted private equity-backed firms that have struggled to attract investors in recent months.
Essar will use the proceeds of the deal to fund a significant expansion programme to strengthen its position in India's oil, gas and energy sectors.
The LSE listing is a further indication that the City has managed to retain its position at the top table in terms of global financial centres. London lost out to Hong Kong on the $2.2bn listing of Rusal earlier this year, but Essar chose London largely because of its links with the Indian market and its global reputation for corporate governance.
More than 80 per cent of FTSE 100 earnings derive from outside the UK and international IPOs had grown into a significant source of revenue for City PR before the recession bit.
There are signs that international listings may be on the rebound after the LSE regained its number one position for IPOs among European stock markets in the first quarter of 2010, according to PricewaterhouseCoopers.
The Finsbury-advised African Barrick Gold was the largest deal during the first quarter and it is set to be joined by Ukrainian egg producer Avangard in the forthcoming months. Avangard handed its IPO comms brief to FD.