The coalition may include some NATO countries and other states.
Britain is in talks with allies to send warships into the Black Sea to protect cargo ships carrying Ukrainian grain.
A coalition of allies will try to break the Russian blockade by providing a "protective corridor" from Odessa through the Bosporus, the British Times has said.
It is noted that the corridor was discussed yesterday at a meeting between the Lithuanian foreign minister and British Foreign Secretary Liz Truss.
The coalition may include some NATO countries and other grain-dependent states. Egypt, which has been hit hard by wheat shortages, is expected to take part in the coalition.