Four people carrying more than 6kg (14lb) of explosives have been arrested near a suburban railway station in the Indian city of Mumbai, police say.
The four were detained at the busy Andheri station after a tip-off.
Police have said they do not know whether the four were intending to detonate the explosives or were delivering them to others.
Last July more than 180 people were killed when seven bombs exploded in trains and at stations in Mumbai.
About 700 people were injured in those attacks.
Dozens of people have been charged with involvement in the attacks, which India blamed on its rival, Pakistan. Pakistan denied any involvement.
The four people arrested on Saturday were carrying trinitrotoluene, usually known as TNT.
"They were arrested with the TNT at Andheri following a tip off," V K Choubey, a senior police officer, told the AFP news agency.
The arrests come days before India celebrates Republic Day on 26 January.
The holiday has often been used as a pretext for launching attacks by separatists and protesters.