Huge mystery spill detected in Baltic off Swedish coast

Coastguard checking ships' routes and says samples being sent for analysis

A massive spill of an unknown substance has been detected in the Baltic Sea off the coast of Sweden, the country's coastguard said on Thursday.

Covering a surface area of 30 sq miles (77 sq km) in both Swedish and Finnish waters, the spill was detected on Wednesday in the Bothnian Sea.