Versalko have preformed at Llangollen before

The 28 performers arrived at Kiev's British embassy on Monday and have refused to leave until they get the necessary documents to come to Wales.

Festival organisers say the difficulties getting performers visas have been "the worst ever"

They say they seem to be experiencing difficulties in the wake of the row over scams involving immigrants from Romania and Bulgaria.

The Ukrainian group Versalko has performed at Llangollen had been due to leave on Friday in order to if complete the three-day coach journey to the festival in time.

We were due to have 2,300 overseas competitors taking part, but the number has fallen to 1700 - mainly because people can't get visas Keith Hall, International Eisteddfod

The annual event begins on Tuesday and the singers are in a race against the clock to get the documents stamped and set out.

Three other groups - another 75 performers - from the Ukraine who are due to perform at Llangollen are still trying to get visas

Keith Hall, competitor's liaison officer at Llangollen said: "It is the worst certainly that I can remember in more than 10 years of doing this job."

"We were due to have 2,300 overseas competitors taking part, but the number has fallen to 1700 - mainly because people can't get visas".

He said he thought the festival was experiencing some kind of "knee-jerk reaction" after the row earlier this year over the suspension of visa applications from Romania and Bulgaria.

Another group from India who had visited the eisteddfod for many years had at first been refused visas and then were only able to get a reduced number, said Mr Hall.