TIANJIN - China's free trade zones (FTZs) are one bright spot in an otherwise dimming economy, as three of them celebrate their first 100 days this week.

The area covered by the Tianjin FTZ, one of the three unveiled on April 21, saw 7,053 new enterprises registered in the first half of 2015, more than double the number in the first half of 2014, as companies eyed the preferential policies to be offered in the zone, according to Jiang Guangjian, deputy director of the zone.

Their registered capital added up to nearly 174 billion yuan (around $28 billion), soaring 248 percent year on year, said Jiang.

Of the new enterprises, 280, about 4 percent of the total, are foreign-funded entities with a gross registered capital of 61.9 billion yuan, accounting for 35.6 percent of the total, Jiang said.

He attributed the increase to cutting red tape, relaxing rules on foreign investment, and the coordinated development of the Beijing-Tianjin-Hebei region.

Jiang also highlighted the importance of expanding the use of Renminbi as a transaction currency in cross-border businesses and investments.

Under a "single-window" service system for international trade, entrepreneurs can register a new company in the FTZ by visiting just one administrative center. Previously, they needed 109 stamps from 18 offices.

As for Beijing-Tianjin-Hebei development strategy, businesses have been encouraged by an integration plan that includes industrial upgrades and better traffic management. Public services will be improved and the area will be made into a more comfortable environment for foreign enterprises to work in.

Exports from the Tianjin FTZ have been spurred by the liberalization. Liu Jiangang, deputy secretary general of the Tianjin municipal government, said exports increased 5.1 percent year on year in the first half, with a 29-percent surge in exports to countries along the Belt and Road regional trade and infrastructure network.

The Belt and Road encompasses more than 60 countries and regions, with a population of 4.4 billion. Those areas accounted for more than a quarter of China's total exports and about a fifth of its outbound direct investment in the first five months of 2015, according to the Ministry of Commerce.

Tianjin is an important hub for the Belt and Road, as are the two other FTZs in Guangdong and Fujian provinces. Their opening in April followed the launch of China's first FTZ, in Shanghai, 18 months ago.

The central government is encouraging the zones to pilot measures to promote growth, although all of them must adhere to the "negative list" approach, which details areas in which foreign investment is prohibited or restricted, ranging from media to non-ferrous metal mining.

The government has said that successful measures piloted in the FTZs will be replicated elsewhere.

The zones' role in reform, trade and investment in new areas is important as the economy moves away from its unsustainable export-dependent model.

"More pilot free trade zones are especially needed in central and western regions to stimulate growth," said Zhang Shuyu, a researcher with the University of International Business and Economics.