Tate Director Sir Nicholas Serota is for many one of the most important and influential people in art, regularly securing a top three placing in Art Review's annual list of the art world's most powerful figures. But he is also subjected to virulent criticism from a number of quarters, in particular from the Evening Standard's provocative art critic Brian Sewell, who regularly uses his column to lambast him for "furthering so many worthless careers".

Few, however, would be able to argue with the fact that Tate Modern, which was converted from a power station under his direction, has been the most enormous success. It celebrated its 10th anniversary this May with the news that over 45 million visitors have passed through its doors since it opened in 2000, more than double original expectations. It is certainly the most popular modern art museum in the world.

The 64-year-old Serota was appointed director in 1988. The son of Stanley, a civil engineer, and Labour peer Baroness Beatrice Serota, he says that there was some parental opposition to his choice of career.

"My mother was quite formidable. She certainly wasn't sure I should be in the art world. Slowly she came to understand that it wasn't such a bad decision and that it didn't mean that I had to abandon her belief that if you work with others you can make the world a better place." He feels strongly that his Jewish family background has had an impact on his life, stating "the values that I learned from my family undoubtedly play a huge part in what I do and the way I try to do it. I work in an institution that is here to serve the public because that is everything I represent.

He is proud that he has introduced so many members of that public to modern and contemporary art. "So many people who never thought they would be interested have found something at Tate Modern that has excited, sometimes perhaps irritated, but certainly engaged their interest. And then so many of those who have visited once seem to want to come back. Over the 10 years we have had an astonishing number of visitors."

The values I learnt from my family play a huge part in what I do

There have been 52 major exhibitions at Tate Modern, a record of which he is also very proud. Perhaps the most memorable displays have been shown in the famous Turbine Hall where contemporary artists have been commissioned to produce new works that used the enormous space in new and varied ways. Among the works shown there were Anish Kapoor's huge Marsyas, a sculpture which spanned the full length and height of the hall.

"The Turbine Hall displays were a big risk and they remain a risk in a way," Serota admits. "No-one had really tried to do something on that scale in a museum for a big audience but the artists have responded brilliantly. The curatorial team has worked to find some challenging artists, some artists whose names were not household names when they took on the responsibility but then they became household names. It was exactly what we should be doing - not doing the obvious."

The main problem he faces is the gallery's sheer popularity. "All too often the galleries are overcrowded, especially at the weekends," he acknowledges. Not surprisingly, given visitor numbers, a decision was made to expand - to build on the derelict oil tanks of the power station - which will almost double the amount of display space available. The project has an estimated cost of £215 million, of which £76.5 million has so far been raised. Building nevertheless started in January.

"We have taken the view that we had sufficient funding to make a good start and to produce something in time for the 2012 Olympics, and we are continuing to raise funds," says Serota. "We have some way to go still but we are confident that we will complete the whole project over the next few years. It will be built as far as we can raise the money."

Funding is an issue that made the headlines recently as demonstrators angrily demanded that Tate rejects funding from BP as a response to the Gulf of Mexico oil leak. Serota, however, stresses that the relationship will continue. "We look for long-term partners and one of those long-term partners is BP. They have been with us for 20 years. We all recognise they have a difficulty at the moment but you don't abandon your friends because they have what we consider to be a temporary difficulty."

One of Tate's new collecting strategies is to focus on art from the Middle East, and in February Tate Modern hosted a weekend of screenings of recent videos from Israel. Were there any repercussions? "It is important for us to show the work of Israeli artists in a context of programmes that includes artists from the Arab world," Serota maintains. "Given the political circumstances in the Middle East, there will always be voices raised against showing work from one or other community. Our job is not to take sides but to try and make people in this country aware of the concerns of artists from that region, their achievements, and some of the tensions of that region which are undeniable."

One area in which Jews have made a big contribution to the art world is as collectors. Serota asserts that figures who have opened their collections to the public - such as Anita Zabludowicz, Frank Cohen and Charles Saatchi, who has just announced that he is donating 200 contemporary works of art to the nation - only serve to complement the Tate's programme.

"The striking thing is that there is a great love of art within parts of the Jewish community, but there is equally a wish to share and a certain sense of obligation that if you have something of value you should share it with others. That is part of the ethic of the community and you see it in the support that came from the Jewish community to create Tate Modern and you see it in the way that collectors are showing their collections. Tate has always been incredibly dependent on the Jewish community for support generally and for the growth of its collections. Only yesterday we celebrated the life and achievements of Mortimer Sackler at which, by coincidence, one of the speakers was Vivien Duffield, and it was of course her foundation that established the Clore Gallery for the Turner Collection. Tate is a prime example of the generosity of the Jewish community."