SANTIAGO, March 5 (Reuters) - Chile's monthly economic activity rose at its weakest pace in nearly four years in January, undershooting market estimates and adding to evidence that an ongoing slowdown in the top copper exporter could be more severe than expected. The IMACEC economic activity index, encompassing about 90 percent of the economy tallied in gross domestic product figures, rose 1.4 percent in January from the same month a year ago, the central bank said on Wednesday. That came in below a Reuters poll forecast for a 1.9 percent rise and is the lowest figure since March 2010, when the country was still reeling from a devastating earthquake. It is also the lowest January reading since the 2009 recession. The weaker-than-expected data follows news last week of anemic manufacturing output, less frenetic retail sales growth and disappointing jobless figures. It puts pressure on the incoming government of Michelle Bachelet, who will be inaugurated on March 11 and who has promised an increase in tax-and-spend policies. Bachelet's chosen finance minister, Alberto Arenas, criticized the policies of the current conservative government for exacerbating the situation by reducing public investment. "The new government is receiving an inheritance from the current administration of a decelerating economy, a low growth inheritance," he said on Wednesday. He stuck to previous pledges of a blitz of 50 reforms in 100 days, but gave no detailed guidance on the timetable. Outgoing finance minister Felipe Larrain warned on Tuesday that the new government's planned tax reforms should be watered down in the context of the economic slowdown. EXPECTING A RATE CUT The downbeat data will also increase expectations that the central bank will continue its easing cycle when it meets to decide the benchmark interest rate next week. The market is already predicting a cut to 4.0 percent from 4.25 percent, after the bank maintained a negative bias when it reduced rates from 4.5 percent last month. "We estimate that these levels of activity continue to make the argument for cuts to the interest rate soon, very probably in the first quarter," said economists at BCI. In the minutes of the February decision published on Wednesday the bank said that all board members "stressed that recent data pointed to a deeper than expected slowdown." It said the "surprise" was that output and consumption continued to grow in line with expectations. Although the rate of growth is slowing, retail sales have remained robust, propping up the economy in recent months. Late Tuesday, Chilean retail giant Falabella reported profit up 15 percent in the fourth quarter. In comparison with December, January's IMACEC decreased a seasonally adjusted 0.6 pct. The December 2013 IMACEC reading was 2.6 percent growth, the lowest of the year.