Chinese hackers have targeted phones used by former U.S. President Donald Trump and his running mate, J.D. Vance, in a breach of a telecommunications network.

Mr Trump’s campaign was informed this week that the telephone numbers of the Republican presidential nominee and his running mate were breached.

Sources say the type of information on phones used by a presidential candidate could be a gold mine for an intelligence agency.

However, it was unclear whether the hackers had gained access to text messages, especially those sent through unencrypted channels.

But Mr Trump’s campaign officials were told that the hackers might still be inside Verizon’s systems.

However, it was unclear whether they were actively trying to extract data from the phone lines.

The revelation came in the closing stages of a campaign in which Mr Trump’s team has also been targeted by Iranian hackers.

The Iranian hackers have repeatedly sent inner-circle spear-phishing emails that were at least partly successful in gaining access to his campaign’s communications and documents.

Following the development, security has been tightened around Mr Trump as a result of assassination threats from Iran.

However, a statement by the campaign spokesman, Steven Cheung, blamed the White House and Kamala Harris for allowing foreign adversaries to target the campaign.

Early this year, security officials also discovered the presence of a China-affiliated hacking group in the American telecommunications system.

Many said the breach could also have far-reaching national security implications.”