(Adds country data, details)
FRANKFURT, Jan 3 (Reuters) - The European Central Bank's purchases of corporate bonds slowed last month to their lowest level since it started buying company debt almost two years ago, data showed on Wednesday.
The ECB has been buying government bonds since 2015, in an effort to boost inflation in the euro zone, and added credit to the programme a year later. It is widely expected to wind down the programme this year, having already reduced its pace to 30 billion euros ($36 bln) per month.
Credit is expected to account for a growing share of the purchases this year as the ECB nears a cap on how many government bonds it can own in countries such as Germany and Portugal.
But Frankfurt bought just 3.08 billion euros ($3.7 billion) worth of company debt last month, less than half the amounts acquired in each of the previous three months.
While purchases of government bonds, the largest component of the ECB's stimulus programme, were also curbed, the reduction there was less marked as they fell to 46.2 billion euros from 50.7 billion a month earlier.
In total, the ECB bought 50.2 billion euros worth of assets in December, a month when it normally reduces the pace of buying due to low trading volumes on financial markets around Christmas.
As has been the case for months, the ECB bought fewer government bonds from Germany, Portugal and Finland than its rules dictate, making up for it with oversized purchases in Spain, France and Italy.
The ECB set out to buy bonds based on how much capital each country has paid into Frankfurt's coffers, which in turn depends on the size of its economy.
But it has had to deviate from this rule, introduced to overcome German scepticism when the scheme was launched in 2015, to avoid hitting a self-imposed ban on owning more than a third of each country's debt.
($1 = 0.8324 euros) (Reporting by Francesco Canepa; Editing by Alison Williams and Susan Fenton)