Musavat Party leader Isa Qambar also said his party would not recognize the outcome of the vote and would struggle "to the end" to obtain justice.
Kerimli said Azadliq would fight "peacefully" to have the results of the polls overturned.
Speaking to journalists earlier in the day, Kerimli had said that, in the event of massive fraud, Azadliq would organize a protest march on 8 November in central Baku. He had also said that the opposition was committed to fight for its rights within the constitutional framework.
"We will defend the rights of the voters through all the constitutional means that exist under the law," Kerimli said. "I can tell you right now that all our protests will have an exclusively peaceful character. We will not give the authorities any excuse to use force against the people."
Addressing reporters at a news briefing, Azadliq election-campaign head Panah Huseyn claimed that nearly 6,000 violations had already been registered by midday.
Huseyn said election workers at some polling stations were marking voters' fingers with washable, rather than indelible, ink. He also reported alleged cases when opposition election observers were denied access to polling stations.
Other Azadliq leaders today pointed to numerous vote irregularities, citing unconfirmed reports that some of their representatives in regional election commissions had been detained.
RFE/RL's Azerbaijani Service reported that the five representatives of the opposition in Azerbaijan's 15-member Central Election Commission demanded today that the commission hold an emergency meeting to assess the extent of the irregularities.
Leaders of the ruling Yeni Azerbaycan (New Azerbaijan) party, in turn, accused Azadliq of violating election laws in at least 10 of the country's constituencies.
None of these claims could be independently confirmed.
Some 1,600 foreign and 17,000 Azerbaijani election observers monitored the polls. Their preliminary conclusions were not expected until late into the night.
Yeni Azerbaycan Secretary-General Ali Ahmadov denied accusations that the vote had been rigged in favor of pro-government candidates.
Ahmadov also implicitly claimed victory in the elections, saying Yeni Azerbaycan had achieved its target of retaining its 75 seats in the Milli Meclis.
Yet, as Kerimli and Ahmadov were making those comments, election officials had still not released any results.
The findings of a U.S.-sponsored exit poll commissioned by the State Department in 65 of Azerbaijan's 125 electoral constituencies had also not been released.
Only turnout figures were available at 10 p.m., local time.
According to the Central Election Commission, less than 50 percent of Azerbaijan's registered voters took part in the polls.
Azerbaijan's election laws say the vote can be validated regardless of the turnout.
Ahmadov of Yeni Azerbaycan also expressed concern over the objectivity of the State Department-commissioned exit poll, saying that relatives of opposition activists were involved in the survey.
The U.S. Embassy in Baku pledged to investigate the allegations.
The Azerbaijani opposition, in turn, has questioned the reliability of another exit poll conducted by two private U.S. companies, saying it could be biased in favor of the government. The poll, conducted in all but one of Azerbaijan's electoral constituencies, showed Yeni Azerbaycan would retain a reduced majority of 56 seats in parliament.
U.S. Ambassador to Azerbaijan Reno Harnish told reporters that some embassy teams had been monitoring the election in various polling stations throughout the country.
"We have 40 embassy teams just like the one that I'm in, observing all day long," Harnish said. "We have a very strong exit-poll team all over the country and you just saw one of the teams operating. And we had the government get the inks and the lamps that it needed to conduct the finger-inking procedure."
Harnish, who toured several Baku polling stations during the day, said he would not comment on the conduct of the election until he gets all information from the embassy monitors.
As Harnish was addressing the media, reports say police had taken position outside the headquarters of the Democratic Party of Azerbaijan (ADP), where Azadliq leaders were meeting.
RFE/RL's Azerbaijani Service reports security officers were checking all cars driving nearby, but were not blocking access to the ADP headquarters.