All of the subway trains currently used in the city are either imported or produced by foreign joint ventures in China.

"The purpose of developing our own subway cars is to lower costs and promote overall industrial capacity," said Wu Xinyi of Shanghai Shentong Holdings Company - a major investor in the city's Metro system.

The cheaper trains won't lead to lower subway fares, however.

"The investment in subway trains only accounts for a small part of our overall investment in the subway," said Wu.

Officials wouldn't say yesterday how many of the domestically produced trains they plan to buy.

Several of the new subway trains are being exhibited at the China International Urban Rail Transport Expo at the Shanghai New International Expo Center.

The six-carriage trains, which look like the current trains operating in the city, were developed by Shanghai Rail Traffic Equipment Company, an arm of Shanghai Electric.

According to Chen Chao, a project manager at Shanghai Metro Operation Company's department of new subway trains, the new trains will be tested for around six months before they are put into use.

The test will check if they work well with current trains and study the levels of electromagnetic fields they create.

"If they produce too much electromagnetism, they will affect all the other moving trains and their inter-communication system," Chen said.

Han Bin, a manager at Shanghai Electric, said domestically made cars will cost "tens of thousands of yuan" less than imported cars or those produced by joint ventures.

The new cars will also be equipped with cameras to monitor each carriage.

The first phase of Metro Line 9 - linking rural Songjiang District with Xuhui District - will open late this year.

Metro operators have spent US$326 million on 51 six-carriage subway trains from the Canada-based Bombardier Transport for the new line.