LONDON - Britain’s Passport Office was forced Wednesday to deploy hundreds more staff to deal with a backlog in applications approaching half a million, as the issue threatened to become a fresh political row.

Many applicants complain they are having to wait weeks longer than normal for new or renewed passports, putting holiday plans in jeopardy with the summer school break just a month away.

The Home Office says it currently has about 465,000 applications. Home Secretary Theresa May, who had previously denied opposition claims of a passports “crisis”, said the problem was caused by a “very, very high” level of applications at the start of the year. But the Public and Commercial Services (PCS) union blamed job cuts and office closures for the long delays.

May said: “We will continue to look at this issue and the Passport Office will put more staff in place and resources in place to ensure they can deal with these applications.”

Immigration Minister James Brokenshire said the Passport Office had already taken on 300 extra employees in the last two years to cope with what was a 12-year high in applications.

But Mike Jones, speaking for the PCS, said the measures were insufficient to deal with a worsening backlog.

“The Home Office and the Passport Office used to have strategies in place for when the figure reached 150,000, that they would put contingency plans in to deal with those amounts,” Jones told BBC radio.

“Now we have seen the figures are up to 500,000 and rising at the moment... so there is clearly a crisis going on within the Home Office and the Passport Office as well.”

Passport Office chief executive Paul Pugh, who has been called to appear before lawmakers next week, said 99 percent of “straightforward” applications were being processed within four weeks.

“We have issued almost three million passports for UK customers in 2014, including over one million issued in the eight weeks since the start of April,” he said.

The passports issue threatens to become another row at the heart of government, hot on the heels of a dispute over the handling of extremism allegations in schools.

Labour’s home affairs spokeswoman Yvette Cooper said May’s answers to parliamentary questions on the passports backlog were “incredibly complacent”.