Germany has imposed an export ban on arms maker SIG Sauer after guns manufactured by the German company were found to have been sold to the Colombian police, German media report.
Under German law, arms exports require a special licence which is not normally granted for countries where there is armed conflict, such as Colombia.
Colombia says it bought almost 65,000 SIG Sauer pistols for its police force from the US Department of Defense.
SIG Sauer denies any wrongdoing.
German newspaper Sueddeutsche Zeitung and broadcasters NDR and WDR say that German export officials imposed the ban at the beginning of July.
The German federal office for export controls has also reportedly launched a probe to determine whether SIG Sauer is a "reliable exporter".
Prosecutors in the state of Schleswig-Holstein raided SIG Sauer's headquarters earlier this month.
The prosecutors were already investigating the company over alleged illegal weapons exports to Kazakhstan and recently widened their probe to include the alleged illegal sales to Colombia.
According to a joint investigation by the Sueddeutsche Zeitung and NDR, SIG Sauer sold the guns to the US knowing they would be exported to Colombia despite not having a licence to do so.
But SIG Sauer says it complied with all the legal requisites required for the export.
Between 2009 and 2011, the company shipped thousands of guns to its subsidiary in the US state of New Hampshire.
German officials say they granted the required licence for those exports after receiving written assurances by US officials that the weapons would remain in the United States.
However, Colombian police officers say they have been issued with SIG Sauer weapons bearing the inscription "Made in Germany".
The Colombian defence ministry confirmed it had purchased almost 65,000 SIG Sauer pistols from the United States since 2006.
Colombian defence officials said they had bought the guns directly from their US counterparts through the Foreign Military Sales Programme.
Under the programme, the US can sell "defence articles and services" to foreign countries when the US president "formally finds that to do so will strengthen the security of the US and promote world peace".
"We are completely calm about this purchase, because it was done legally government to government. If Germany requires some sort of explanation, it should come from the US," a Colombian defence official told newspaper El Tiempo.
In a statement, SIG Sauer also said that after their sale to the US, the responsibility for the weapons lay with Washington.
"We have International Import Certificates (IC) issued by the relevant US authorities for all of our shipments. Through an IC the country declares that the goods - once they have entered the country - will come under its rules governing exports and therefore come under its responsibility," the statement reads.
SIG Sauer said it was not aware of any wrongdoing on its part and would fully co-operate with the investigation.
According to German government guidelines, a country which does not stop an unlicensed shipment could be banned from receiving future arms exports.
US authorities have not yet commented on the allegations.
The US spent billions of dollars helping equip and train the Colombian military and police in its effort to combat drug trafficking and left-wing rebels.
More than 220,000 people are estimated to have been killed in five decades of armed conflict in the South American nation.