Indian police said on Saturday that they had arrested two men who helped the Mumbai attackers get mobile phone cards they used to stay in touch during the three-day rampage.

Police in the eastern city of Kolkata identified the men as Tausif Rehman and Mukhtar Ahmed, who were picked up on Friday after investigators traced some of the Subscriber Identity Module (SIM) cards recovered from the gunmen.

'We are questioning them about procurement of SIM cards used in Mumbai,' Jawed Shamim, the deputy commissioner of detectives in Kolkata, told Reuters.

The arrests are further evidence of Indian complicity in the three-day rampage New Delhi has blamed on Islamic militants from neighboring Pakistan, which has raised tensions between South Asia's longtime foes, both of which have nuclear weapons.

Airports in New Delhi, Bangalore and Chennai remained on high alert for a fourth day on Saturday, with extra security personnel deployed after India's civil aviation authority said it had received intelligence that attacks could be planned.

Security was also high in the north Indian town of Ayodhya on Saturday, the 16th anniversary of the razing of the Babri mosque by a Hindu extremist mob which set off Hindu-Muslim riots that killed thousands. A makeshift Hindu temple is still on the site.

At least 700 extra officers were protecting the site, District police chief RKS. Rathore told Reuters.

Fifteen Hindu activists demanding a permanent temple be built were arrested in nearby Faizabad while Muslim activists who ordinarily fly a black flag on the anniversary opted not to.

'We are not making any public protest this time in view of the large-scale carnage by terrorists in Mumbai,' activist leader Yunus Siddiqui told Reuters.

Hindu nationalists burned five Pakistani flags in front of the temple site on Saturday to shouts of 'Down with Pakistan!'

'We decided to also condemn the terror unleashed by Pakistan on our country,' a spokesman for the group, Sharad Sharma, said. 'And what could have been a better way to condemn than setting ablaze the flags of that country?'

At least 171 people were killed in the attacks last week in which 10 gunmen struck two luxury hotels and other landmarks in India's financial capital.

Zardari hoaxed

Police said new details of local Indian help were being pursued after the arrests of Rehman and Ahmed.

Rehman, a clerk, used a dead relative's identity documents to acquire the 22 SIM cards, which he later sold to Ahmed, Shamim later said. Both men were charged with conspiracy and forgery.

Ahmed was a street vendor and three-wheel taxi driver in Kolkata, Shamim said. He was arrested in New Delhi.

Shamim said it was not immediately clear how the SIM cards were passed to the gunmen, whom investigators have said used the phone to stay in touch with their controllers in Pakistan during the 60-hour rampage.

Mumbai police have said the gunmen were controlled by the Pakistan-based Lashkar-e-Taiba (LeT) group blamed for earlier attacks in India including a 2001 assault on India's parliament that very nearly sparked a war between India and Pakistan.

LeT is on U.S. and Indian terrorist lists and Indian police say two of its operations leaders, who were designated terrorists by Washington in May, coordinated the Mumbai rampage.

The latest arrests come amid public anger at intelligence failures in preventing the attacks. India's newly appointed home minister on Friday admitted there had been lapses.

Police this week said they had arrested an Indian citizen in February, Faim Ansari, carrying maps of Mumbai that highlighted several of the targets hit in the attack.

Also on Saturday, Pakistan's Dawn newspaper reported that Pakistan put its forces on high alert after a hoax caller pretending to be India