Deputy Works Minister Datuk Mohd Zin Mohamed said the land in Kedah, Penang, Perak, Selangor, the Federal Territory, Negri Sembilan and Johor was acquired in stages between 1980 and 1988.

He said highway concessionaire PLUS Expressway Bhd (PLUS) had spent almost RM1 billion to upgrade the 823km highway.

"The concession agreement is not forever and therefore we cannot terminate their contract as we like," said Mohd Zin in reply to Datuk Raja Ahmad Zainuddin Raja Omar (BN-Larut).

He said terminating the contract would affect the company's performance as PLUS had one of the biggest market capitalisations in the stock exchange.

"The increase in toll rates, every three years, is meant to cover the cmoney spent by PLUS but the hike is still minimal.

"Our toll rates are among the cheapest in the region," he added.

Mohd Zin said the government had directed studies to be carried out on the impact of toll hikes on highway users.