"Nitish Kumar telephoned Rajnath Singh and assured him that the state government will take the investigations to a logical conclusion," sources close to the Chief Minister said.
Singh was present at the 'hunkar rally' which was addressed by the party's Prime Ministerial candidate.
BJP patriarch L K Advani also spoke to Kumar over phone.
Five persons were killed and 78 injured in seven blasts that took place at the railway station and around the Gandhi Maidan, the venue of the rally.