Russian media reports say China is close to reaching a major arms deal with Moscow that would bolster its air force with 48 new Russian fighter jets.

The Kommersant daily quotes Russian defense officials as saying the financial terms of the $4 billion deal have already been agreed upon. If signed, it would be one of the largest arms deal between the two countries in the past decade.

But the paper says the deal is being held up by Moscow's insistence that Beijing does not make counterfeits of the aircraft that could be sold to other countries at lower prices. China has in the past used foreign technology to develop its own combat aircraft.

The Su-35, also known as the Flanker-E, is the latest in a series of Russian-built fighter jets. The single-seat aircraft is capable of traveling up to 2,400 kilometers per hour and has a range of 3,400 kilometers.

China announced earlier this week that its 2012 military budget would top $100 billion dollars, an increase of over 11 percent from last year.

Many of China's neighbors are concerned that Beijing's military buildup is being used to enforce its increasingly assertive claims in the East and South China Seas.