Berlin - A group of artists has refused to participate in an ambitious project to restore the original artwork on the longest remaining strip of the Berlin Wall in a dispute over payment and the way the work is being carried out.

At least 15 of the 86 artists who have been invited to re-paint the images they drew two decades ago are boycotting the project, their spokesman, Bodo Sperling, said Thursday.

The 2.2-million-euro (2.9-million-dollar) restoration is taking place along a colourful 1.3-kilometre concrete strip known as the East Side Gallery, often dubbed the world's biggest open-air gallery.

Sperling told the German Press Agency dpa that the artists were not willing to work for the one-off payment of 3,000 euros being offered by organizers.

The artists had also raised objections to the manner in which the project was being financed and the way the funds were being distributed.

"Several hundred thousand euros have been used for purposes other than intended. The financing plan of the whole project is incomprehensible," Sperling said.

The company responsible for the distribution of funds, STERN, has rejected the accusations. "The figures have been checked by us according to legal requirements and make sense," STERN spokesman Helmut Schermeyer told dpa.

The costs would also be checked by the state-run German Lottery group that provides the money to renovate the paintings, he said.

Some artists also did not see the sense in re-doing old paintings on the wall, Sperling said. There were also some who would like the concrete canvas dismantled while others prefer to have younger artists work on it, he added.

Schermeyer doubts this will happen. Since the East Side Gallery was declared a historic monument in 1991 it is not possible to create paintings other than the original ones or to dismantle the stretch of the Berlin Wall, Schermeyer explained.

Images on the preserved portion of the former border wall between East and West Berlin range from the abstract to portraits of former politicians of the time.

One of the most popular is Russian artist Dimitri Vrubel's "Brothers Kiss," showing Soviet president Leonid Brezhnev embracing East Germany leader Erich Honecker.

Vrubel had yet to decide whether to join the boycott, his spokeswoman Irina Slinchok said in Berlin.

Some 118 artists from 21 countries painted the East Side Gallery over a six-month period in 1990, in the wake of the fall of the Berlin Wall and before the German Democratic Republic ceased to exist.

Their original 105 paintings showed the artists' visions and ideas dealing with the political changes.

Earlier this month, several artists returned to repaint their work on the white-washed wall ahead of the 20th anniversary of the fall of the Berlin Wall in November 1989. (dpa)