Green groups want to narrow the differences in environmental standards between the SAR and the mainland.
Mr Tung said co-operation with the Guangdong authorities would be strengthened through a new joint working group on sustainable development and environmental protection.
Air pollution in Hong Kong is believed to be aggravated by cross-border trucks filling up with the mainland's lower standard diesel, which is high in sulphur dioxide content.
Friends of the Earth assistant director Plato Yip Kwong-to said a common standard should be established to minimise cross-border pollution.
'Even if we can't have a common standard quickly, we should gradually narrow the gap,' Mr Yip said.
But Green Power executive director Man Chi-sum said that the mainland would find it hard and too expensive to upgrade standards quickly.