Media playback is unsupported on your device Media caption Eamon O Connor explains why he believes police may have been spying on him

An investigative journalist has told BBC Scotland he believes Police Scotland may have been monitoring his communications illegally.

Eamon O Connor said a police source informed him he was being targeted as he investigated the unsolved murder of Emma Caldwell.

Mr O Connor presented a BBC programme earlier this year examining what went wrong with the police investigation into the 10-year-old case.

Police Scotland did not deny his claim.

But the force said it did not comment on individual cases.

It emerged last month that two un-named UK police forces had been involved in spying on journalists and their sources.

'Dependable source'

The Sunday Herald newspaper claimed at the weekend that Police Scotland was one of them, and that the force's Counter Corruption Unit used spying powers to uncover a journalist's sources without getting judicial approval.

Mr O Connor told the BBC's Scotland 2015 programme that he did not know for sure that he had been monitored

But he added: "Recently I was contacted by a very dependable source who knows Police Scotland very well and he warned me that he had been told explicitly that the Counter Corruption Unit, which is designed to catch police doing things they shouldn't do, has been monitoring journalists' communications with police sources for some time.

"He believed that I had been one of those people targeted and more significantly he thought I had been targeted without judicial approval.

"I can only assume that (my BBC investigation) has caused some concern inside Police Scotland. I know that it has because I've had contact from senior sources inside Police Scotland, but I don't know if anyone inside Police Scotland has been so concerned that they've decided to monitor my communications to see who I've been speaking to."

Reserved matter

Mr O Connor said he was concerned that the possibility of being spied upon by the police would "intimidate and impede" whistleblowers and people who want to come forward to tell the truth about something which they believe should not have happened.

Emma Caldwell's body was found dumped in a ditch in Lanarkshire in May 2005. Police launched a massive murder investigation which has cost £4m, but no one has ever been convicted of her murder.

Four Turkish men were charged over Ms Caldwell's death, but were later released and did not stand trial.

The Interception of Communications Commissioner's Office (IOCCO) has said it was investigating possible breaches of the code of practice at two police forces but would not name them while its inquiry was ongoing.

Labour lodged an emergency motion at the Scottish Parliament on Wednesday calling for "full transparency" from Scottish government ministers over what they knew about the allegations that Police Scotland had spied on journalists.

The Scottish government said it would not be appropriate to comment further while the IOCCO investigations into the alleged breaches were ongoing.

A spokeswoman added: "However, if there are any issues arising out of these investigations, they should be fully addressed by the appropriate bodies when they have concluded."