(Reuters) – Russian President Vladimir Putin said on Thursday that he had signed a decree saying foreign buyers must pay in roubles for Russian gas from April 1, and contracts would be halted if these payments were not made. “In order to purchase Russian natural gas, they must open rouble accounts in Russian banks. It is from these accounts that payments will be made for gas delivered starting from tomorrow,” Putin said. “If such payments are not made, we will consider this a default on the part of buyers, with all the ensuing consequences. Nobody sells us anything for free, and we are not goi…