KUALA LUMPUR (Reuters) - The veteran chief minister of the Malaysian state of Sarawak died on Wednesday in a fresh blow for Prime Minister Najib Razak who was counting on him to help secure victory in upcoming elections.

Adenan Satem, 72, died of a heart attack, media said. There was no official confirmation of the cause.

Adenan was one of Najib’s closest allies, whose popularity helped the ruling Barisan Nasional alliance secure a landslide victory in the Sarawak state elections last year.

Najib was counting on Adenan to help him in a general election that the prime minister is expected to call this year.

Najib is mired in a multi-billion dollar graft scandal involving state fund 1Malaysia Development Berhad (1MDB). The fund is being investigated in at least six countries, including the United States, Singapore and Switzerland.

Najib has denied wrongdoing.

Sarawak rallied behind Adenan as he brokered greater autonomy for the resource-rich state on the island of Borneo and dealt with long standing issues such as recognition of native land rights since becoming chief minister in 2014.