BP (BP.N) on Monday agreed to buy stakes in gas-heavy exploration areas off the coast of Mauritania and Senegal from Kosmos (KOS.N), days after announcing the long-awaited renewal of an onshore oil concession in Abu Dhabi.

The combined deals are worth around US$3.4 billion and will add valuable oil and gas reserves to BP's books that have seen resources shrink on the back of divestments it needed to make to pay for the 2010 Gulf of Mexico oil spill.

They follow BP's purchase of a stake in Eni's giant Zohr gas field offshore Egypt for US$375 million last month and come at a time of rising oil prices.

BP said on Monday it had agreed to buy a 62 per cent stake and operational control of Kosmos' Mauritania exploration blocks, which include the Tortue discovery, estimated by Kosmos to contain more than 15 trillion cubic feet (tcf) of gas.

In comparison, Eni's Zohr field, the largest discovery ever made in the Mediterranean, is estimated to contain 30 tcf.

Gas from the Tortue field is set to be exported from a liquefied natural gas (LNG) facility, giving BP an opportunity to grow in a highly competitive sector in which rival Shell (RDSa.N) took the lead earlier this year with the US$54 billion acquisition of BG Group.

BP also agreed to buy a 32.5 per cent stake in Kosmos' Senegal blocks, spending in total around US$1 billion on the Kosmos deal. Kosmos is a Dallas-based energy company.

"We believe the basin will become an important profit center for our upstream business," said Bernard Looney, chief executive of BP's upstream business.

On Saturday, BP closed the renewal of a 40-year-long participation in the Abu Dhabi Company for Onshore Petroleum Operations (ADCO) after two years of negotiations, taking a 10 per cent stake in return for a roughly two per cent share in BP.

The concessions included in the deal have total resources of 20-30 billion barrels of oil equivalent.

"BP's shopping spree is the company's response to what the investor community has long been concerned about: long-term growth and resource sustenance," said Brendan Warn, analyst at BMO Capital Markets, who has an "Outperform" rating on the stock.

"BP's timing might have also been triggered by what it sees as a likely recovery in the oil price and asset values over 2017."

Oil prices have climbed above US$50 a barrel in recent weeks as the world's biggest oil producers have agreed to reduce output to stem global oversupply.

Shares in BP were up 0.6 per cent at 10:27 a.m. GMT, outperforming the oil and gas companies index, which was down 0.15 per cent.