UPDATE 1-Colombia central bank to auction repo worth $3.9 bln on Monday

BOGOTA, July 27 (Reuters) - Colombia's central bank will auction off a 23-day repurchase agreement (repo) worth 7 trillion pesos ($3.9 billion) to boost peso liquidity in the market, it said on Friday.

The auction will take place on Monday between 11:30 a.m. (1630 GMT) and 11:45 a.m. local time and will have an interest rate of between 5 percent and 6 percent.

The bank also said that if all the resources were not placed for the 23-day repo, it would auction off the remaining pesos at a 7-day maturity.

The monetary authority will also carry out the traditional one-day repo auction of 8.2 trillion pesos.

On Friday, Colombia's central bank unexpectedly lowered its benchmark interest rate for the first time in over two years to shield Latin America's No. 4 economy from declining global prices for oil and coal, the country's top exports.

$1=1,791.12 Colombian pesos