Spiritual advisers and families of inmates on death row in Indonesia have been told to prepare for executions tonight as coffins were ferried to the prison island of Nusa Kambangan on Thursday morning.

Lawyer Ricky Gunawan, who acts for Merri Utami, a former Indonesian migrant worker on death row, said her spiritual adviser had been informed the executions would take place overnight.

“The priest who assists Merri, he was told to prepare for tonight,” said Gunawan, the director of the Community Legal Aid Institute (LBH), which is representing Utami, and this week filed a clemency appeal to the Indonesian president, Joko Widodo, on her behalf.

Syed Zahid Raza, the deputy Pakistani ambassador in Jakarta, said the family of a Pakistani man on death row, Zulfiqar Ali, had also been informed that he would be executed on Thursday night.

On Thursday, name tags were issued to family members, government officials and spiritual advisers – who provide comfort and guidance to prisoners in their final hours – to specify their relationship to the inmates, an indication that executions were imminent.

Gunawan said: “The name tags were also different. Name tags displaying who they are and which areas they allowed to access.”

Family member(s) of the listed inmates receive(s) this name tag, indicates that the execution will occur tonight. pic.twitter.com/2ZyQKwd4QW — LBH Masyarakat (@LBHMasyarakat) July 28, 2016

Ambulances carrying the coffins arrived on Thursday morning at the port of Cilacap, the town on the Javanese mainland that is a gateway to the island penitentiary.

Fourteen prisoners on death row, including inmates from Nigeria, Pakistan, India and South Africa, and four Indonesians, have been moved to isolation holding cells on Nusa Kambangan. Thirteen are men and one – Utami – is a woman. All were found guilty of drugs offences.

Human rights groups argue that many of the cases of prisoners on death row in Indonesia – including some of the 14 facing execution this week – are marked by questionable and inhumane practices, including beatings, torture and forced confessions.

An Amnesty International report detailed how Ali was allegedly beaten and tortured to confess he was in possession of 300g of heroin, saying he required stomach surgery after sustaining beatings in police custody.

The embassy of Pakistan has stepped up diplomatic efforts over recent days to stop the execution of Ali, while India’s minister of external affairs, Sushma Swaraj, tweeted that “last-minute efforts” were also underway to save Indian national Gurdip Singh.

We are making last minute efforts to save him from execution on 28 July. /2 @NukteVivek — Sushma Swaraj (@SushmaSwaraj) July 27, 2016

There are also questions surrounding the case of Nigerian national and church leader Humphrey Jefferson. A lawyer for Jefferson argues there is evidence he was framed by a co-worker at the restaurant he formerly ran.

Jefferson’s diaries, shared with his lawyer during a visit to Nusa Kambangan, show pages filled with religious songs and prayer, written during his 13 years on death row. One verse he penned reads: “Every moment I wake, you are here with me. Never let me go. Never let me go.”

Pages from the diary of Humphrey Jefferson, known as Jeff, who is on death row in Indonesia facing imminent execution. Photograph: Humphrey Jefferson/LBHM

Clemency appeals for Utami and Jefferson were filed by lawyers from LBH earlier this week. To proceed with the executions while those appeals are still pending would be contrary to the law, Gunawan said.

“I think this shows a systematic and blatant disregard and violation of the Indonesian laws, particularly on clemency and rules of execution,” he said.

A vigil has been planned in Jakarta on Thursday evening, where 1,000 candles will be lit in front of the state palace in peaceful protest.

Indonesia resumed executions in 2013, ending a four-year unofficial moratorium on the death penalty. In face of strong international criticism, Widodo has defended the use of capital punishment, arguing the country is facing a drug emergency.

The attorney general’s office has provided scant details about the latest executions, the third round to take place under Widodo.

The Indonesian government had said it intended to avoid the “soap opera” that ensued last year, when the execution of two Australian men, Andrew Chan and Myuran Sukumaran, and six others drew global condemnation.

Relatives of death row prisoners arrive at Wijayapura port to visit Nusa Kambangan prison on Thursday. Photograph: Ulet Ifansasti/Getty Images

However, the attorney general, HM Prasetyo, did confirm on Wednesday that the third round was fast approaching and that 14 prisoners would be executed.

“If nothing’s has changed, there will be 14 people,” Prasetyo told reporters.

Muhammad Rum, a spokesman for the attorney general, said the executions were the “implementation of our positive laws” and would not be delayed. All the cases have gone through a long legal process including appeals, he said. “They all have been given chances at all stages.”

Notice was given to prisoners on Tuesday that their executions were to be carried out, but if they were to go ahead on Thursday night it would appear to be in contravention of Indonesia’s own regulations, which say at least 72 hours’ notice must be given.

According to Amnesty International at least 165 people are on death row in Indonesia, and more than 40% of those for drug-related crimes. Executions for drug-related crimes are in violation of international law.