The under-pressure lira held steady against the dollar on Wednesday after U.S. President Donald Trump's national security adviser said Turkey had made a "big mistake" in not freeing a U.S. pastor held on terrorism charges.

The lira has lost 37 percent of its value this year in a crisis triggered by concerns over President Tayyip Erdogan's influence on monetary policy and excerbated by the dispute with Washington.

U.S. National Security Adviser John Bolton told Reuters during a visit to Israel that Ankara "made a big mistake in not releasing Pastor (Andrew) Brunson".

The case was likely to continue to add to the lira's woes, said Per Hammarlund, chief emerging markets strategist at SEB.

"Ultimately, they will release Brunson but it will take a while and as long as there is a risk to U.S. dollar flows to Turkish banks or to Turkey in general, then the lira will be under pressure," Hammarlund said.

"I wouldn't be surprised if we see another bout of volatility in the lira and a sharp weakening again."

The lira stood at 6.0820 at 0933 GMT, compared with a close of 6.0600 on Tuesday. Trade was thinner than usual and probably mainly offshore after Turkish markets closed at midday on Monday for a week's holiday to mark the Muslim Eid al-Adha festival.

Brunson, who has lived in Turkey for two decades, has been detained for 21 months on terrorism charges, which he denies, and is now under house arrest.

Trump, who counts evangelical Christians among his core supporters, has become a vocal champion of the pastor's case.

"Every day that goes by that mistake continues, this crisis could be over instantly if they did the right thing as a NATO ally, part of the West, and release (him)... without condition," Bolton told Reuters.

Brunson's lawyer said he planned to appeal to the constitutional court for the pastor's release, after being rejected by a lower court last week.

A court in Turkey's Izmir province rejected the appeal for release, saying evidence was still being collected and the pastor posed a flight risk.

In an interview with Reuters on Monday, U.S. President Donald Trump said he would give Turkey no concessions in return for the release of Brunson. Ankara has not responded to Trump's comments.