Protest rallies have been held across India by hard-line Hindus to campaign against a proposed shipping canal project between India and Sri Lanka.
Hindu activists say the canal project will damage Lord Rama's bridge
Massive traffic jams were reported in many places and trains delayed in many parts of the country.
Protesters say the project will destroy a bridge they believe was built by Hindu God Ram and his army of monkeys.
Scientists question the belief, saying it is solely based on the Hindu mythological epic Ramayana.
Commuters in the capital, Delhi, were stuck in traffic jams for hours as Hindu hard-line groups, Vishwa Hindu Parishad (World Hindu Council) and Bajrang Dal, blocked roads at various places.
A large number of policemen were deployed in the city to maintain order and a number of protesters were detained.
Road blocks were also held in Bhopal, the capital of the central state of Madhya Pradesh, on the Delhi-Agra highway and on the Jaipur-Agra highway.
Roads were blocked in many places
Train services were disrupted in many places across northern India.
The Sethusamudram Shipping Canal Project proposes to link the Palk Bay with the Gulf of Mannar between India and Sri Lanka by dredging a canal through the shallow sea.
This is expected to provide a continuous navigable sea route around the Indian peninsula.
Once complete, the canal will reduce the travel time for ships by around 650km (400 miles) and is expected to boost the economic and industrial development of the region.
Hindu activists say dredging the canal will damage the Ram Setu (or Lord Ram's bridge), sometimes also called Adam's Bridge.
The say the bridge was built by Lord Ram's monkey army to travel to Sri Lanka and has religious significance.
Scientists and archaeologists, however, say there is no scientific evidence to prove their claim.
They say it has never been proved that Lord Ram's monkey army existed at all as described in the Hindu epic Ramayana.
The Archaeological Survey of India says the bridge is not a man-made structure, and is just a natural sand formation.