Europe's border guard agency Frontex says it is deploying 293 officers and 15 vessels to the Greek islands in response to a request from Athens for assistance in managing an "unprecedented migratory pressure."

Frontex said Tuesday the deployment began the day before under a new operation called Poseidon Rapid Intervention. Greece has requested more assistance in surveying its borders that are part of the EU's external borders, the Warsaw-based Frontex said.

Thousands of asylum-seekers are arriving by boat on the Greek islands from the Middle East, Africa and Asia.

Frontex officers, interpreters and document experts will assist in identifying and fingerprinting the arriving migrants.

Frontex said it aims to scale up the mission in Greece over time to 400 officers with vessels, vehicles and other technical equipment.