Authorities beefed up security on Saturday for a planned marathon for men and women, a day after police arrested 400 protesters from an Islamic group that has branded the race obscene and vowed to block the runners.

Several Islamists and two police officers were injured during Friday's street clashes in Lahore, the venue of Sunday's marathon and the cultural capital of Pakistan's eastern Punjab province. Police have since increased security for the race.

The marathon is expected to draw dozens of athletes from 16 countries and 10,000 Pakistanis, including women and children. But hard-line Muslims have pledged to disrupt the race, saying Islam prohibits women from participating in such events.