LONDON – Suspected Somali pirates have carried out a series of hijacks and attempted attacks off Somalia, raising fresh concern that piracy networks are again operating along one of the world’s key maritime corridors.

UK Maritime Trade Operations (UKMTO) in London reported a hijack involving a tanker northeast of Mareeyo, Somalia, saying unauthorized people took control of the vessel and moved it south inside Somali territorial waters. UKMTO advised vessels to transit with caution and report suspicious activity.

The Joint Maritime Information Center at Naval Support Activity Bahrain has raised the threat level for the Somali coast and Somali Basin to “substantial,” citing an oil-products tanker held by pirates, a Somali-flagged fishing vessel hijacked near Xaafuun and an attempted boarding about 83 nautical miles off Eyl.

The activity appears concentrated off Puntland, where suspected pirates seized a fuel tanker between Hafun and Bandarbeyla and later hijacked a St. Kitts and Nevis-flagged cargo vessel carrying cement off Garacad.

The incidents mark a sharp escalation after years of reduced Somali piracy, which declined under international naval patrols and improved ship security. The latest reports do not yet show a return to the peak piracy crisis of the early 2010s, but they point to organized groups again testing commercial shipping.

Maritime authorities are urging vessels near Somalia to maintain heightened vigilance, review anti-piracy procedures and report suspicious approaches immediately.