Turkish President Recep Tayyip Erdoğan’s efforts to persuade U.S. President Donald Trump to limit an investigation into Turkey’s state-run Halkbank is under scrutiny in Washington again, after Trump’s former national security advisor mentioned his concern about the issue in his forthcoming book, the New York Times reported.

John R. Bolton reported in his forthcoming book his concern that the president was effectively granting personal favours to Erdoğan, the NYT said.

Halkbank was indicted by U.S. prosecutors in November for evading U.S. sanctions on Iran. A Manhattan jury previously convicted Halkbank deputy CEO Mehmet Hakan Atilla of conspiring to help Iran evade sanctions in a criminal trial that ended in January 2019.

“President Trump has been carrying water for President Erdoğan and Turkey’s state-owned Halkbank,” The NYT quoted Senator Ron Wyden of Oregon, the top Democrat on the finance committee, as saying.

Trump in 2017 was asked by Rudolph W. Giuliani during an Oval Office meeting with Rex W. Tillerson, then the secretary of state, to help secure the release of a Turkish gold trader at the centre of Halkbank’s sanctions-evasion efforts, the NYT said.

Turkey wanted Reza Zarrab released so that he would not testify against Halkbank’s top officials or implicate members of Erdoğan’s family or the president himself, the NYT said, citing former Turkish government officials.

But Zarrab, who had hired Trump’s personal lawyer Giuliani to help secure his release, later agreed to testify against Halkbank official Atilla.

Halkbank signed a $125,000-per-month contract in 2017 with Ballard Partners, a firm run by Trump’s top Florida fundraiser Brian Ballard.

Erdoğan, in a series of phone calls and in-person conversations in 2018 and 2019, repeatedly tried to influence Trump, asking the U.S. president to limit additional enforcement against Halkbank, the NYT said.

Turkish Ministry of Treasury and Finance Berat Albayrak, who is also Erdoğan’s son-in-law, took up the case, pressing Treasury Secretary Steven Mnuchin on the matter, while the former project manager of Trump Towers Istanbul also made appeals, the newspaper said.

The U.S. Justice Department moved to indict Halkbank, after Turkey launched a military operation in north Syria in October.