Byzantine lead seal

[R R]

Hi colleagues,

need help with identification of this Byzantine lead seal (15.5 grams, 29 mm), search in Dumbarton Oaks returned no results.

Obverse: nimbate saint, looks similar to depictions of St. Basil from 11th century.

Reverse:

 .. O  B A? N? .
... M P? O ? ..
... E  C T V ..
... A P N ...
    .....