Senegal’s government has summoned the Gambian ambassador to protest against the execution of two of its nationals.
President Macky Sall said he would expel the ambassador if he did not attend a meeting on Wednesday.
Two Senegalese men were among nine prisoners executed in The Gambia on Sunday on the orders of President Yahya Jammeh.
He ignored pleas from the African Union (AU) to halt the executions – the first in The Gambia in 27 years.
Mr Sall said he was dismayed and surprised that the executions took place without Senegal being informed through diplomatic channels.
The Gambia had shown “disregard” for the Senegalese government and had failed to act in a “neighbourly spirit”, he added.
“I have asked the prime minister to summon The Gambian ambassador so as to inform him of the Senegalese position and of our regret at this unacceptable attitude,” Mr Sall said.
Woman executed
Earlier, The Gambia’s Interior Ministry said the prisoners were shot dead by firing squad on Sunday.
Mr Jammeh has vowed to kill all 47 death-row inmates by mid-September.
“By the middle of next month, all the death sentences would have been carried out to the letter; there is no way my government will allow 99% of the population to be held to ransom by criminals,” President Jammeh said in a speech, which was broadcast on national television on 19 August, marking the Muslim festival of Eid.
It was not clear what crimes each of the nine prisoners were executed for.
Amnesty International and the European Union’s foreign policy chief, Catherine Ashton, have urged The Gambia to stop the executions immediately.
Many of The Gambia’s death row inmates are former officials and top military officers who have been detained for treason since 1994, when Mr Jammeh took power in a coup.
One woman was among those executed, the Interior Ministry said, listing crimes such as murder, treason, arson, drug and human trafficking as being punishable by death.
The death penalty was abolished when former President Dawda Jawara led the country but reinstated in 1995 shortly after Mr Jammeh seized power.