Three cities in Guangdong province have agreed to connect their subway lines, a step forward for the province to promote internal economic integration.

According to the agreement, Shenzhen's subway line 16 will extend to reach Fenggang township in Huizhou, while Shenzhen's subway lines 6 and 11 will connect with Dongguan's R1 and R3 lines.

The traffic integration is expected to accelerate the economic cooperation of the three cities.

Other agreements on regional innovation, quality control of agricultural product and cultural cooperation were also signed.

Under the deals, Shenzhen-based companies including automaker BYD and telecom equipment producer Huawei Technologies will build research and development bases in Dongguan and Huizhou.

Huang Yebin, Party chief of Huizhou, said Huizhou, an agricultural powerhouse, will benefit the most in the integration.