Support for Kishida's government has tumbled to its lowest level since he took office on growing anger about the Liberal Democratic Party (LDP) lawmakers not fully disclosing their ties to the church, known for its mass weddings.

Abe was shot during an election rally and the suspected killer said his mother was bankrupted by the church, which critics call a cult, and blamed Abe for promoting it.

Kishida instructed the culture minister to prepare an investigation into the church under the Religious Corporations Act.

Speaking to parliament, Kishida apologised that many of his LDP members had ties to the church, which he said undermined public trust in the government.

The premier said he was "taking seriously" allegations that the church left many followers impoverished and disrupted their families.

He said he had no personal relationship with the church, although nearly half of the LDP's lawmakers have disclosed connections since Abe's assassination. The party says there is no organisational link to the church.

Kishida said the government had received more than 1700 requests for help over financial trouble and mental health problems related to the church. He vowed to expand support for victims.

The government's panel of experts said in a proposal issued on Monday that dissolution of the church should be an option considered by investigators.

The Unification Church was founded in South Korea in 1954 by Sun Myung Moon, an anti-communist and self-declared messiah.

It built ties with politicians to attract followers and gain legitimacy, according to Hiroshi Yamaguchi, a lawyer who has worked on cases against it. Politicians gained access to church members for help with campaigns, he said

The church says it has been vilified and members have faced death threats since Abe's murder.

Australian Associated Press