HAVANA (Reuters) - Communist-ruled Cuba said on Wednesday it had removed Marino Murillo from his post as economy minister so he could focus more on his role spearheading the country's market-style reforms.

Murillo will be replaced by another veteran politician, Ricardo Cabrisas Ruiz, who has been responsible for the country's international economic relations, in particular its recent debt restructuring. Both are vice presidents.

The cabinet shuffle comes days after President Raul Castro and Murillo told Cubans to brace for tougher times due to a cash crunch and lower oil assistance from key ally Venezuela.

"This decision is due to the need for Murillo... to concentrate his efforts on the tasks linked to the update of the Cuban economic and social model," read an official announcement placed in state-run media.

Since taking over from his ailing brother Fidel in 2008, Raul Castro has turned much of Cuba's state-controlled agriculture over to cooperatives and allowed self-employed contractors to operate small businesses.

But much remains to be done to update one of the world's last Soviet-style command economies, Cuba acknowledges.

Murillo, who was designated economy minister in 2014, is chief of the commission charged with carrying out reform.

(Reporting by Nelson Acosta and Sarah Marsh; Editing by Shri Navaratnam)