British Transport Police have re-opened an investigation into anti-Israel posters which were put up across the London underground.

The inquiry into more than 200 posters, which were placed on tube trains during Israel Apartheid Week in February, was closed last Thursday after police said they had pursued all lines of inquiry.

But Detective Inspector Gabriel Oresajo, who is heading the probe, told the JC that it had been re-opened on Friday morning.

He confirmed that officers were pursuing a line of inquiry relating to the alleged involvement of activists with ties to two institutions in the capital.

DI Oresajo said: “If we get anything from that it may open up a new avenue. It’s our last line of inquiry.”

The decision came after the UK Lawyers for Israel group contacted DI Oresajo and London Mayor Boris Johnson, who is chairman of Transport for London, last month.

UKLFI chair Jonathan Turner called on police to take action against the activists who had put up the posters.

In response, Mr Johnson wrote: “I recognise the considerable concerns regarding the advertisements denigrating Israel that were illegally posted in tube trains on 21 February.

“Placing posters on trains is a criminal act and this material has no place whatsoever on the Transport for London network.”

He added: “TfL takes acts of vandalism extremely seriously.”

The posters showed mocked-up versions of BBC reports and claimed that the corporation's coverage of the Middle East conflict was biased in favour of Israel.

Mr Turner said he hoped action would be taken against offenders, adding: “We are also grateful to Mayor Boris Johnson for taking a personal concern in the matter. We hope this example will be followed by the next mayor.”