A person who was in constant touch with the four suspects who were arrested from Hardiwar, has been arrested by the special cell of Delhi Police on Thursday.
The Delhi Police on Wednesday placed all four suspects involved in the Pathankot terror attack to 15 days police custody.
According to sources, the four were planning to carry out terror strikes in the ongoing Ardh Kumbh mela in Haridawar.
The arrested suspects' links with the Pathankot terror attack is being probed.
The suspects were also planning to strike Delhi as they had carried out reconnaissance of malls in the national capital.