Labour has suffered a second cyber attack on its digital platforms within the space of 24 hours, the party said.
A party spokeswoman said the latest distributed denial-of-service (DDoS) incident was being dealt with "quickly and efficiently".
Earlier, leader Jeremy Corbyn expressed concern after the party experienced what it described as a "sophisticated and large scale" DDoS attack on Monday.
However, PA understands it was a relatively "low level" attack.
The National Cyber Security Centre confirmed it would not be investigating the matter further, while a source said there was no evidence of "state-sponsored activity".
DDoS attacks – where hackers flood a target's online platforms with traffic from various sources, causing them to slow or crash – are considered relatively common.
Following the latest incident, a Labour spokeswoman said: "We have ongoing security processes in place to protect our platforms, so users may be experiencing some differences.
"We are dealing with this quickly and efficiently."
Speaking at a campaign event in Blackpool following the first incident, Mr Corbyn said he was "nervous" about what it could mean for the rest of the General Election campaign.
"We have a system in place in our office to protect us against these cyber attacks, but it was a very serious attack against us," he said.
"So far as we're aware, none of our information was downloaded and the attack was actually repulsed because we have an effective in-house developed system by people within our party.
"But if this is a sign of things to come in this election, I feel very nervous about it all because a cyber attack against a political party in an election is suspicious, something one is very worried about."