Turkmenistan and Azerbaijan have traded accusations over a contested patch of oil field in the Caspian Sea.
Turkmenistan’s Foreign Ministry said on June 19 it was officially protesting what it called "illegal measures" by Azerbaijani border guards against a Turkmen vessel that was carrying out "research" in the disputed zone.
The statement accused Azerbaijan of "provocations" but gave no further details.
Earlier, Azerbaijan's Foreign Ministry summoned the Turkmen ambassador to Baku to warn against what the ministry described as Turkmen attempts to explore the disputed zone.
Baku calls the oil field Kapaz, while Ashgabat calls it Serdar.
Both sides claim ownership.
In 2008, the two countries' leaders signed an agreement calling for the two Caspian littoral states to refrain from exploratory or extraction activities in the area until the dispute is resolved.
Based on reporting by Interfax and turkmenistan.ru