Six months after superstorm Sandy, the city's subway system is still stumbling.

The number of delay alerts sent to riders was up 29 percent in the first three months of this year over the same period in 2012 because of Sandy damage, according to a report from the Straphangers Campaign.

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"Months after battering New York City, superstorm Sandy continues to hurt subway service," said Gene Russianoff, staff attorney for the Straphangers Campaign.

Sandy shuttered the entire system for days after hitting the city on Oct. 29. Still out of commission are the A train at the Rockaways and Manhattan's new South Ferry Station, which could be down for years, the MTA has said.

The agency acknowledged the extensive damage to the system has caused an increase in service delays, but it declined to say whether the increase is the 29 percent in the campaign's report. Still, MTA spokesman Charles Seaton said commuters may have to deal with increased delays for some time.

"This is going to be an issue for quite a while. There was significant damage to the system, and we are continuing to make repairs," Seaton said.