The police on Sunday afternoon raided the BJP office at Gulab Bagh in Varanasi on the orders of the district administration to find out whether outsiders were camping there.
The police seized a large quantity of publicity material from an SUV parked just outside the premises, even though they did not find any outsider.
Later in the day, district magistrate Pranjal Yadav, who is also the returning officer for the Varanasi parliamentary constituency, issued orders to return the seized items.
"There is nothing illegal and objectionable about the campaign material," Yadav said.
The BJP, which had recently held a protest against the election commission over the denial of permission for a rally by Narendra Modi in Varanasi, later lodged a complaint with the poll watchdog for carrying out a raid without an arrest warrant.
Senior BJP leader Lakshman Acharya said, "Cops carried out a raid without a search warrant. No outsider was found at the party office."
The police also raided several locations to trace AAP volunteers who had arrived in large numbers from across the country to campaign for party convener Arvind Kejriwal, who is contesting against Bharatiya Janata Party's (BJP's) prime ministerial nominee Modi and Congress candidate Ajay Rai in the holy city.
The raids followed reports that hundreds of supporters of various political parties from other places had stayed back in Varanasi, which goes to polls on Monday in the last leg of the nine-phase Lok Sabha elections.
The district administration had set a deadline of Saturday 6pm for all outsiders to leave the city.
When the raid at BJP office was going on, AAP leader Ramanand Rai was standing close by.
He had arrived there in a four-wheeler with two others. When BJP workers spotted Rai, they chased him away.
During the course of the high-voltage campaign in Varanasi, a large number of BJP and AAP supporters had arrived for campaigning.
Many of the BJP workers had come from Gujarat, Rajasthan and Chhattisgarh — three states ruled by the party. AAP volunteers had arrived from New Delhi, Jaipur and other parts of the country.
These volunteers were staying at party offices, lodges and hotels all across the city.
On several occasions, the AAP had accused BJP workers of attacking the rookie party's volunteers.
Former Delhi minister and AAP leader Somnath Bharti was recently assaulted, allegedly by BJP workers, at the Assi Ghat during a talk show of a news channel.
Besides, AAP leader Arvind Kejriwal had to face an ink attack during his first road show in Varanasi on March 25.