BISHKEK -- The turmoil in Kyrgyzstan over the arrest of opposition party leader Omurbek Tekebaev has taken a new turn after his political party claimed that he was targeted for prosecution to suppress evidence that a cargo plane which crashed outside the capital in January was carrying goods belonging to President Almazbek Atambaev.
A spokesman for Atambaev denied the claim, calling it a "lie."
Meanwhile, Kyrgyzstan's Foreign Ministry on March 1 also rejected the allegations, saying that Turkey's ambassador had called the opposition's purported evidence "fake."
A lawyer for Tekebaev's Ata-Meken (Fatherland) party asserted on March 1 that law enforcement officers detained Tekebaev upon his arrival from Cyprus via Turkey on February 26 in order to prevent him from publicizing documents she said showed that goods aboard the cargo plane belonged to Atambaev and his wife.
"In order to gain [possession of] the documents before they become public the law-enforcement officers detained Tekebaev at the airport and made sure that lawyers could not reach him," the lawyer, Taalaigul Toktakunova, told journalists.
"Tekebaev was unable to make the information public on time," she said.
The MyCargo 747-400 crashed on January 16 near Bishkek, killing four crew members and 35 people on the ground and setting off speculation about the ownership and destination of its cargo.
At a news conference in Bishkek, Toktakunova presented a document with what she said was Turkish Security Service letterhead. She read aloud from what she said was a Russian translation of the document that said Ankara's security service had conducted investigations into the plane crash and concluded that "mobile phones, computers, other electronic devices, cash, valuable metals and stones belonged to the president of Kyrgyzstan, Almazbek Atambaev, and his spouse."
The text she read also said that the cargo's transportation to Bishkek has been organized by a Turkish national known as "Rattlesnake" and several citizens of Turkey and Kyrgyzstan.
But Kyrgyzstan's Foreign Ministry said Foreign Minister Erlan Abdyldaev met personally in Bishkek with Turkish Ambassador Metin Kilic after Toktakunova's press conference to discuss the opposition's claims.
In a statement, the ministry said Turkey's ambassador told Abdyldaev that the Turkish Security Service "does not work in such a way and doesn't give documents with their letterhead to anyone."
The ministry statement said Kilic also told Kyrgyzstan's foreign minister that the document shown to journalists on March 1 by Toktakunova was "a forged document -- a fake."
Tekebaev is deputy chairman of a parliamentary commission set up to investigate the plane crash, and had been actively involved in the parliamentary probe.
Residents of the village where the plane crashed have said that looting broke out soon after it went down, telling journalists that first responders took many smartphones and other electronic devices that had been part of the cargo and were found in the debris.
WATCH: Plane Crashes Into Kyrgyz Homes, Killing Dozens
Residents also found printed instructions for electronic devices written in Kyrgyz and Russian, prompting speculation that the goods were being shipped to Kyrgyzstan.
Tekebaev has accused Kyrgyz authorities of trying to cover up information about the crash, citing contradictory statements by Kyrgyz officials and those of the company that owned the plane.
Atambaev did not visit the crash site or meet with survivors in the hard-hit village, prompting criticism and speculation about his motives.
'Unjust, Politically Motivated'
Almaz Usonov, chief of the presidential administration's information-policy department, said the lawyer's claim was "not just absurd" and "not just a lie."
"In fact, what Tekebaev's lawyers did is an obstruction of the investigation," Usonov told RFE/RL. "It is an attempt to politicize the case and hijack public opinion by attracting citizens' attention to something else."
Meanwhile, hundreds of supporters of Tekebaev protested for a fourth straight day, demanding his release, and State Committee for National Security (UKMK) chief Abdil Segizbaev warned lawmakers not to "impose any pressure" on investigators.
Speaking at a protest in Bishkek, former President Roza Otunbaeva called Tekebaev's arrest "unjust and politically motivated."
On February 27, a court ordered Tekebaev held in custody until April 25. He is being investigated in a corruption and fraud case related to allegations that he received a $1 million bribe from a Russian businessman while serving as deputy prime minister.
A former ally, Tekebaev fell out with Atambaev in 2016 over constitutional amendments that critics suspect were aimed at prolonging Atambaev's power after a November 19 presidential election in which he is barred from running by a single-term limit.
Supporters of Tekebaev say they believe the criminal investigation is aimed at preventing him from running for president.
Atambaev has defended Tekebaev's arrest, saying on February 28 that it was not politically motivated.
Tekebaev is the third member of Ata-Meken to be detained by authorities for questioning in recent weeks.