South Korea's biggest and most bizarre manhunt, linked to a ferry disaster in which hundreds drowned, has come full circle at the compound of a sect known for its organic ice cream as police on Thursday used earth movers to search for tunnels.

Police have twice raided the grounds of the Evangelical Baptist Church in Anseong, a two-hour drive south of Seoul, as they hunt church co-founder Yoo Byung-un, 73, South Korea's most wanted man since the Sewol ferry sank in April killing more than 300 people, mostly children from one school.

But so far, Yoo, a businessman and photographer who was once jailed for fraud, has eluded capture in a case which has become an embarrassment for authorities already under pressure for their handling of the disaster.