Correction: 29/07/2016: An earlier version reported that two Nigerians, one South African and one Indonesian were executed. That was incorrect. Three Nigerians and one Indonesian were executed.

The Indonesian government has carried out four of the planned executions of 14 people found guilty of drug crimes, Al Jazeera has learned.

The convicts were shot by firing squad at the Nusa Kambangan penal island shortly after midnight on Friday local time (17:00 GMT on Thursday) amid pouring rain, according to TV reports.

Deputy Attorney General Noor Rachmad also confirmed the executions to reporters, according to the AFP news agency. But Rachmad did not say why the 10 other drug convicts had not been executed. 

Al Jazeera's Step Vaessen, reporting from Jakarta, said among those who were executed were three Nigerian citizens and one Indonesian.  

"All the others are still waiting their trials to be re-examined," our correspondent said. "It's not very clear what actually were the last conclusions [and] why these executions didn't take place. But the government is saying it has something to do with legal issues."    

The lawyer of Pakistani prisoner Zulfikar Ali had earlier told our correspondent that his client was not among those who had been executed.

Al Jazeera's Vaessen said there had been "a lot of pressure" until the last minute to stop the executions. 

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The executions were the third set carried out since President Joko Widodo took office in October 2014. 

Widodo's two-year-old administration will have executed more people than were executed in the previous decade. Fourteen were put to death last year. But one prisoner, a woman from the Philippines, was spared the death penalty at the last minute. 

The European Union and the UN High Commissioner for Human Rights had called on Indonesia to impose an immediate moratorium on executions, and the Indian and Pakistani governments also made urgent efforts to save two nationals among the condemned.

The Indonesian government said the death penalty is necessary for narcotics-related crimes because the country was facing a drugs epidemic, particularly affecting young people.

But critics argue that capital punishment is not an effective deterrent and some have also questioned the accuracy of the government's drug abuse statistics.

The government of Jokowi's predecessor did not carry out executions between 2009 and 2012, but resumed them in 2013.

Source: Al Jazeera and agencies