The officials said a suicide bomber was able to detonate an explosive vest inside the building in the centre of Misrata, a coastal city about 200 kilometres (125 miles) east of Tripoli.
"Three men belonging to the Islamic State jihadist organisation carried out a suicide attack against the court complex in Misrata... killing four people and wounding 15 others," General Mohammed Ghassri, a spokesman for armed forces in Misrata that are loyal to the country's internationally backed government, told AFP.
Misrata is home to powerful armed forces who were the backbone of an offensive that routed IS from the coastal city of Sirte in December 2016.
That offensive was backed by Libya's UN-endorsed Government of National Accord (GNA), one of two main rival governments that emerged from the chaos that followed the 2011 ouster of long-time strongman Moamer Kadhafi.
There was no immediate claim of responsibility from IS for today's attack, but the jihadist group remains a force in Libya despite losing control of Sirte.
The US military last month carried out a wave of air strikes on IS in Libya, killing 17 people on September 22 at a desert camp 240 kilometres (150 miles) southeast of Sirte.
The US Africa command said the camp was used to move jihadists in and out of the country, store weapons and plot attacks.
In August, IS claimed responsibility for an attack in which 11 people were beheaded at a checkpoint manned by forces loyal to military strongman Khalifa Haftar.
Nine soldiers and two civilians were killed in that attack in the Al-Jufra region about 500 kilometres (300 miles) south of Tripoli.
Disclaimer: No Business Standard Journalist was involved in creation of this content
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
