"The ruling Congress has criticised the erstwhile Asom Gano Parishad (AGP) government under Prafulla Kumar Mahanta down the years for being involved in such killings, there have been so many probes but till now the culprits have not been identified which is a failure of the government, which has been in power for last three terms", Sonowal told a felicitation programme at Chabbua in upper Assam.
"They (Congress) are in power for the last three terms and now and then the chief minister charged Mahanta with being involved in secret killings. But our question is why the government has failed to convict any accused", he asked.
"Prime minister Manmohan Singh is representing Assam but till now no action has been taken," he added.
On the infiltration issue, the BJP leader, a former General Secretary of the influential All Assam Students Union (AASU), alleged that Gogoi had "gifted state land to immigrants at the behest of Bangladesh President Sheikh Hasina.