The incident happened at 5:45 am at Ashoka Park in Punjabi Bagh when the labourer was hit by a beam, PTI reported.
"The labourer was guarding a beam when it hit his shoulder," DMRC spokesperson Anuj Dayal said, adding that he was rushed to a nearby hospital where he succumbed to his injuries.
"However, there was no structural collapse," he said. This is the third accident in the last two weeks in metro construction sites.
On July 12, six persons were killed and 15 others injured when a pillar of an under-construction Delhi Metro bridge collapsed near Lady Sriram College in South Delhi's Lajpat Nagar.
Just a day after the incident, at least six persons were injured in another accident at the same site during clearance of the debris, according to PTI.
In the first head to roll for the accident at its Jamrudpur site, Delhi Metro had recently shifted a senior official in-charge of the section which witnessed collapse of an under-construction bridge in south Delhi killing six persons.
DMRC managing director E Sreedharan ordered repatriation of Vijay Anand, director (project) of Delhi Metro, who was the director in-charge of the Central Secretariat - Badarpur line of Phase-II which is under construction.
