Plans to spend over £1m redeveloping a Southfields mosque may be approved by Wandsworth Council on Thursday despite strong opposition from neighbours.

Erected in 1926 The Fazl Mosque, also called the London Mosque, on Gressenhall Road, is the oldest purpose built Ahmadiyya mosque in the UK and has been the movement’s global HQ since it was forced out of Pakistan in 1984.

It is also home to Mirza Masroor Ahmad, the elected spiritual leader of the Ahmadiyya Muslim community.

The mosque insists that the redevelopment is purely to provide fit accommodation for its current congregation and not to attract more worshippers, as some neighbours fear.

Mosque leaders said that it has on average about 300 worshippers but on special occasions there are up to 600 which means some have to pray outside – sometimes in the rain.

But the council, which is due to decide whether to approve the plans tonight, Thursday, July 14, has received over 100 objections from people who believe the new buildings would be too large and would put too much of a strain on parking and traffic at prayer times.

Proposed building works include the replacement of the administration block and multi purpose hall, constructing new residential accommodation in Melrose Road and the felling of trees on the site.

The council has also received many letters in support of the plans, and officers are recommending they are approved, subject to a legal agreement.

One supporter, Ejaz Ahmad, of Gressenhall Road, said on the council's planning website: "The first purpose built mosque in Britain deserves to be updated and brought into the 21st century, not only for our community but also for those who come from all over the world to worship."

Michael Struther Kennedy said in objection: "The scale of the proposed development is totally out of scale with the local neighbourhood and will lead to an increase in the number of attendances at the mosque and it's associated facilities."

A spokesman from the London Mosque said: "The new development plans ensure that the facilities are modernised and updated to provide reasonable facilities for the worshippers.

"Whilst we appreciate that there is a perception that a bigger building will mean more people we believe if the plans are looked at objectively and reasonably it will be seen that there will be no material increase in the number of people frequenting the site.

"In fact all that we are proposing is to consolidate the existing areas to ensure those praying in the outside now have a roof over their heads and provide a more suitable residence for our leader."