KYIV -- Media watchdogs have called on Ukrainian authorities to investigate intimidation and attacks against journalists from Skhemy (Schemes), a joint investigative project by RFE/RL and UA: Pershy television, after one of their cars was torched.

The International and European federations of journalists said in a statement on August 18 that a campaign of harassment and intimidation, including suspected surveillance and arson attacks, was aimed at "muzzling" the journalists' investigations.

The day before, the car of one of the team members was set on fire outside Kyiv, which investigators said was caused by "an external ignition source." No one was hurt in the incident.

"It is essential that investigative journalists can freely and critically report on corruption and wrongdoing of state officials," IFJ General Secretary Anthony Bellanger said in the statement.

"Surveillance and the attack against this team are worrisome blows against press freedom that can't go unpunished. We stand in solidarity with the victimized journalists and call on the authorities to protect them from these attacks," he added.

A similar statement from the Committee to Protect Journalists urged Ukrainian authorities to find the perpetrators of the torching of the and "hold them to account."

Skhemy reporters were recently working on a story revealing how the transport of high-level state officials is breaking traffic rules.

During the production of the program, the journalists repeatedly voiced concerns about being under surveillance.

Skhemy reporter Mykhaylo Tkach said earlier in August that he believed he had found signs of surveillance in his apartment.

"Authorities also must thoroughly investigate the surveillance allegations" made Tkach, said Gulnoza Said, the CPJ’s Europe and Central Asia program coordinator.

"By reporting on corruption, investigative journalists at Schemes are doing an important service for the public, and the authorities should ensure their safety," Said added.

RFE/RL acting President Daisy Sindelar has expressed distress over the arson attack, saying that while no one was injured, the broadcaster remains "concerned that this incident appears aimed at intimidating RFE/RL's reporters and contributing to a threatening environment for journalists across Ukraine."

"Schemes is an award-winning investigative team whose work is vital to the public interest of all Ukrainians. We urge Ukrainian authorities to ensure that our colleagues can work safely and without fear," she added in a statement on August 17.