* GDP grows 6.18 pct yr-yr in Q2 vs 6.56 pct in Q1
* Oil output falls to 2.11 mln bpd on oil theft
* Agriculture, services, construction drive non-oil growth (Adds quote, background, details)
ABUJA, Sept 6 (Reuters) - Nigeria's economy grew at a slower rate in the second quarter than the previous quarter, as oil output from Africa's largest producer slipped due to theft and pipeline shutdowns, data showed on Friday.
The economy, Africa's second largest, grew 6.18 percent year-on-year in the second quarter, a touch lower than the previous quarter's 6.56 percent, the National Bureau of Statistics (NBS) said.
Crude oil output averaged 2.11 million barrels per day (bpd), down from 2.29 million bpd in the first quarter.
"While the oil sector experienced production challenges, the non-oil sector output increased in the second quarter," the NBS quarterly report said.
"The non-oil sector growth was driven by growth in activities recorded in the agriculture, airlines, hotels ands restaurants, as well as building and construction sectors."
Nigeria is growing as an investment destination due to its huge potential consumer population of almost 170 million and improved fiscal and monetary stability.
However, its oil industry is being hampered by theft and to a lack of fresh investment due to the delay of a key energy law, which has been in political dispute for years. (Reporting by Joe Brock; Editing by Ruth Pitchford)