The union of Colombian footballers called on authorities to halt all domestic matches because of political instability in the country on Thursday, just a month before the Copa America is due to kick off in Colombia and Argentina.

Colombia has been hit by a wave of protests since late April with riot police wielding tear gas and stun grenades clashing with crowds in many of the country's biggest cities.

Four games in continental cup competitions were moved from Colombia to Paraguay and Ecuador last week due to the unrest.

Hours after the union's appeal, a Copa Libertadores match in Barranquilla between America de Cali and Brazil's Atletico Mineiro was halted several times as players were affected by tear gas fired outside the stadium.

The first half took more than an hour to complete.

At one point the players were removed from the pitch due to the affects of the gas. The match was played to a conclusion, with Atletico winning 3-1.

On Wednesday, players and coaches from Colombia's Junior and Argentine club River Plate struggled with tear gas in another Libertadores tie in Barranquilla.

The Colombian league playoffs are scheduled to take place on Sunday with two semi-final games slated. However, the last of the quarter-finals, due to be played on Friday between Deportivo Cali and Deportes Tolima, has been postponed.

In an appeal to the Colombian Football Federation, the league and their own clubs, players with the Acolfutpro union said that “until the public order situation that affects the entire country and puts our wellbeing at risk is not resolved, we ask you not to schedule any more games in domestic tournaments.”

In an open letter, the union said “professional footballers stand with the Colombians who are demanding a better country.”

The move comes just 25 days before the national side is due to face Argentina in a World Cup qualifier in Barranquilla.

And on June 14, Colombia is set to host the first of 15 games in the Copa America tournament, which features 10 South American countries.

The tournament is the oldest in international football and is being held by two countries for the first time, with Colombia and Argentina sharing the duties.

The kick-off is in Buenos Aires on June 13 and the final is scheduled for Barranquilla on July 10.

(Reporting by Andrew Downie in London; Editing by Stephen Coates/Peter Rutherford)