* Existing deal was meant to expire in 2024
* Production to date exceeds 3 billion barrels of oil
* Azerbaijan has criticised BP for output decline
* BP splashes out on deals in recent weeks (Updates with details, context)
Dec 23 (Reuters) - Oil major BP has agreed withAzerbaijan to extend a contract to develop the country's biggestfields by a quarter of a century to 2050 in a move to unlockbillions of dollars of fresh investments in the Caspian Seadeposits.
The existing production sharing deal was due to expire in2024 and talks to extend it have been slow because ofdisagreements between partners in the BP-led consortium, sourcestold Reuters earlier this year.
The extension of the Azeri contracts adds to the flurry ofdeals BP signed in recent weeks, including buying stakes in gasexploration areas off the coast of Mauritania and Senegal, andrenewing an onshore oil concession in Abu Dhabi.
BP said the consortium and Azeri state oil firm SOCAR onFriday signed a letter of intent to continue developing the giant Azeri-Chirag-Guneshly (ACG) offshore fields until2050.
It said it had agreed the key commercial terms for thefuture development while the deal was due to be finalised in thenext few months.
The shareholders in the consortium include BP, Chevron, INPEX, Statoil, ExxonMobil, TPAO,ITOCHU and ONGC Videsh.
"ACG is known as the 'Contract of the Century'. It is veryimportant to Azerbaijan ... We can now look ahead to many moreyears of ACG's success," the statement quoted SOCAR's presidentRovnag Abdullayev as saying.
The existing deal was signed in 1994 and became the firstsuccessful agreement between a former Soviet Union republic andoil majors to develop energy resources. BP said the new dealwill bring many thousands of jobs in the years ahead.
BP came under fire from Azeri President Ilham Aliyev earlierthis decade when the country's leader criticised the oil firmfor lower than promised output levels.
With current output of 620,000 barrels per day, the fieldshave produced a total of over 3 billion barrels of oil since thestart of the project, with around $33 billion of investment.Their remaining reserves are estimated to contain several morebillions of barrels of oil. (Reporting by Dmitry Zhdannikov, editing by David Evans)