Argentine President Cristina Fernandez de Kirchner on Monday put seven new Chinese-made trains in operation in the capital city of Buenos Aires.

The nine-car trains are the first batch of 25 Chinese trains bought by the Argentine government to modernize and expand the Sarmiento Line, a commuter rail network serving the city and its suburban areas.

"This investment represents an unprecedented qualitative leap" in the city's transportation system, Fernandez was quoted as saying by state-run news agency Telam.

"Yesterday 241,000 passengers could travel, but starting today almost 400,000" will be able to use the expanded service, she added.

Highlighting the trains' security features, Interior and Transportation Minister Florencio Randazzo revealed that the trains "have an intelligent closing system" that prevents them from running until the doors are properly shut, and video cameras are installed in all cars.

He also noted that the conductor's cabins are glass-enclosed "so passengers can see whether the driver's condition is what it should be."

"This is wonderful, because this line transports a large number of people, who are now able to travel better," said Diana Gallo, a commuter.

In recent years, commuter train accidents in Buenos Aires have made headlines around the world, including a 2012 incident that left some 50 people dead and hundreds of others injured, and another one last October that left about 80 passengers injured.