German leader Angela Merkel was hit by a tomato thrown by a protester attending a pre-election tally in Heidelberg on Tuesday.

The 63-year-old Chancellor came under literal and actual fire from hundreds of protesters voicing their upset over her 'open doors' policy during the 2015 migrant crisis.

Police said two tomatoes were thrown during different parts of the Chancellor's speech with one striking her left hip.

Scroll down for video

At least she's wearing red! German Chancellor Angela Merkel looks at a stain on her jacket after being hit by a tomato during a campaign event at the University Square in Heidelberg

One of her aides was also hit by the flying fruit as the words 'liar' and 'hypocrite' rang in her ears.

The noisy demonstration was fresh evidence that not all votes are guaranteed at the general election on September 24 when she seeks a fourth term in power.

Some 3,000 people were at the rally and those who demonstrated against her were angry at her refugee policies which have seen over a million unvetted immigrants enter the country in the last two years.

'If we made a mistake, then it wasn't in taking in people, ' Mrs. Merkel said in defence of her decision to open the doors to migrants in 2015.

'But rather that we didn't pay attention to the fact that people in Jordan, Lebanon, Turkey and Syria didn't have enough to eat, weren't getting an education and put themselves into the hands of people smugglers.'

Brushing it off: Mrs Merkel can be seen wiping off some of the tomato stains on her jacket

Under attack: One of the fruits thrown by a protester hidden in the crowd

Anger: The 63-year-old Chancellor came under fire from hundreds of protesters voicing their upset over her 'open doors' policy during the 2015 migrant crisis

Police spokesman David Faulhaber said today that they are now investigating against persons unknown on suspicion of attempted bodily harm and attempted property damage.

Mrs. Merkel appeared later in the day at a Stuttgart campaign event wearing the same red jacket.

Mrs. Merkel has been heckled during several campaign events, mostly by supporters of the Alternative for Germany (AfD) party which has attracted many of her CDU party supporters into its ranks.

Although widely tipped to be returned to power, the AfD is expected to win big in the election and send MPs into the national parliament for the first time. It is already represented in state assemblies.